In the last 20 years, there has been a quiet revolution in the way we fall in love, not just on dating websites, but on Facebook, Twitter, Second Life…

Crammed into the top shelf of my bookcase, I discover a ream of continuous form, 11 x 15, green-lined computer paper. You know, the kind with the rows of holes on either side that was once used for dot matrix printers? I bring the document into the kitchen. My husband is cooking supper, my 14-year-old son doing his homework. I flash the ream of paper at my husband.

"You're kidding me," he says.

I sit down at the table and begin to read. Soon I am crying. "Are you crying because you're happy or sad?" my son asks, alarmed.

I can't really answer him. The ream of paper is a time machine. Six months of emails from me to my husband, from back when we first met. He asked me out on our first date online, which might not seem a big deal, but believe me it was in 1990. "Would you like to go for a beer sometime?" Nine little words that will be imprinted on my memory for ever.

My husband and I met while working at a company in Cambridge, Massachusetts, called Thinking Machines – manufacturer of the Connection Machine, one of the fastest parallel processing supercomputers in the world. Thinking Machines' motto was: "We're building a machine that will be proud of us." It was an audacious, ahead-of-its-time company. In fact, it was the third company ever to register a dotcom domain name. We had email before virtually any corporate offices had email.

In the late 1980s, there were no mobile phones, few personal computers, certainly no Facebook or Twitter, and before my employment at Thinking Machines I communicated with colleagues the old-fashioned way: telephone, actual real conversations and manila inter-office envelopes. But when I began at Thinking Machines, I was introduced to this newfangled thing called email.

16 February 1990 Hi hon. What a day. Sidewalks are covered with ice. Lots of car accidents. It's supposed to snow through tonight and into the morning. Anyway, I was wondering. What do you think about a visit from yours truly Sunday evening? I don't have to work on Monday so I don't have to get up at the crack of dawn. Would that be OK? I would really love to see you.

A few months after my husband and I met at Thinking Machines (he was on a summer internship, I was employed full-time), he left to go to Wesleyan University in Connecticut. We were deeply, head-over-heels in love – Wesleyan was only two hours from Boston – we could make it work. Besides, we had a secret weapon. Rather then having to rely on a shared dorm phone in some abandoned hallway like all the other long-distance couples, we had email. Between the hours of nine to five, we could communicate with each other almost instantly. We would make it through the school year no problem. Or so we thought. My emails tell a different story.

22 February 1990 I want to make sure it's OK if I come up and visit. I know you talked about needing space. And I understand if you would like the weekend to yourself. But I really want to see you. Tell me what you want. Tell me what you need. I just hope it's me.

The comforting smell of butter and onions fills the room. My husband stands at the stove, his back to me. My son sits on a stool, doing his maths. But I am somewhere else. I've been catapulted into my 25-year-old self, back to a time when my love for my husband was obsessive, intense, all-encompassing. Clearly, reading these emails, he was all I thought about. I was lovesick, in the way only a twentysomething can be.

27 February 1990 "But I love your feet only because they walked upon the Earth and the wind and upon the waters, until they found me."

My God – quoting Neruda? Did I do any work at all? It's a wonder I wasn't fired.

14 March 1990 Hi hon. Got your message. I'm so glad you can come on Friday. So does dinner at home appeal to you? Candlelight. Soft music. Me? I love you as much as I love pad thai. And that's a lot.

It's hard not to cringe. I was so young. So clichéd. Trying so hard to act like an adult. But I knew this was the man I was meant to marry. The question was, did he?

19 March 1990 Thank you for driving me home! It meant a lot to me. I was not in the mood to take the bus. Also wanted to make sure everything was OK. You seemed weird when you left. Just asking. Have a great day!

Hmmm.

21 March 1990 Still confused about what you are saying. Are you saying you think we have too many difficult times and not enough good times? Are you saying you are getting tired of the difficult times and that you think they are too many?

Oy.

The irritating thing about this document is that it contains only my emails to him. I can only guess at his responses:

I'm trying to write a paper.

You're emailing me too much.

A very, very attractive and sexy girl named Maya is putting the moves on me and I'm finding it a little bit hard to resist.

If I think about how many days of my life I've wasted waiting for a new email from a special somebody to appear in my inbox, I'm sure it would add up to months. This ream of paper marks the beginning of that "waiting obsession". Twenty-two years ago, my waiting was a five-day-a-week, nine-to-five gig. I didn't have email (or even a personal computer) at home. I could sign off at night, knowing I was offline and there wasn't anything I could do about that. But now the waiting is 24-7. You cannot shut it off. Ever. I hate the addictiveness of it all. The extremes. The dopamine rush when you get what you've been waiting for. The utter disappointment when you don't. If I had known back then that this is what it would come to, riding that hamster wheel for the rest of my life, would I have been so eager to embrace this new connectivity? I can't say for sure. Still. I wouldn't be married to my husband without it. Email is what kept us together; it was our own personal Connection Machine. It saved us.

Here are the facts. In the bleak midwinter of 1990, the odds on us making it as couple were not in our favour. We were living 120 miles apart. He was a college student; I was a buyer at a company that made supercomputers. He went to keg parties; I went on business trips to visit capacitor manufacturers. But we had this lifeline. This immediate and intimate way of being in touch.

I embarked upon a subtle campaign to bring my husband back to Boston for the summer.

2 April 1990 Cannot connect to eagle.wesleyan.edu using telnet.

4 April 1990 Cannot connect to eagle.wesleyan.edu using telnet.

5 April 1990 Just wanted to let you know something might be wrong with your email, if you even get this, but you probably won't because something seems to be wrong with your email. Love ya!

6 April 1990 Not sure you got last three messages cause something weird is going on with wesleyan.edu. Keeps saying host is unavailable.

6 April 1990 Host is unavailable. Call me at work, hon.

9 April 1990 Can't wait! See you tonight at the field! Meet at five? We can grab a quick bite before.

9 April 1990 Sorry, hon, I emailed that last message to you by accident. That was supposed to go to Joe. Well, not just Joe. A bunch of us went to play softball, not just me and Joe. Hope everything's well!

9 April 1990 Joe's a sales rep.

10 April 1990 Thanks for your calming words. I miss you so much. A very busy week for me, too. Sure, I'd love to see you this weekend, but have plans Friday night. Come Saturday. We can have brunch.

14 May 1990 What do you think? $600 a month. Summer sublet: large, one-bedroom apartment with living room, kitchen, bathroom, bedroom and pantry. Huge amounts of closet and storage space. Hardwood floors and lots of windows. Close to Union Square. 30 minutes by foot to MIT. Even closer to Harvard. Big enough for a couple.

My son peers over my shoulder. I cover the page with my arms. "This is the story of how your father and I fell in love," I say. "You're too young for this. But I'll save it for you for when you're older."

"That's all right," my son says.

"No, you'll want it. When you're a man. And we're dead. It will mean something to you. It will be romantic."

"He's not reading it," my husband says. "That's just between you and me."

18 May 1990 Yes, I want and need something special. In fact, I need something special quite a lot. Do you have something special you would be willing to share with me?

OK. Maybe he's got a point.

This September, we will celebrate our 20th wedding anniversary. Like most couples now, we live out a great deal of our relationship online, but the internet these days is mostly reserved for conducting the business of everyday family life.

Do you have the phone number of that electrician?

Home by seven.

Can you pick up milk? Fat-free, not 2%!

Would our relationship have survived that first year if not for email? I don't think so. I can just picture that dorm phone ringing and ringing and nobody picking it up. My husband asked me out over the internet, we flirted and fell in love over the internet, and we have stayed connected and in love over the internet.

The very last email in the document:

21 May 1990 You have successfully completed your freshman year of college. You are now a sophomore. I am so proud of you. And now as a reward you get to the spend the summer with me! And I have cleared out two big drawers. And two little drawers. And half the medicine cabinet and almost half the closet. And I am saving half the bed for your bod. Kisses.

Comment Is Free: Emily Band, 19, met her boyfriend Tom Cuffe, 19, 'below the line'

Emily Band and Tom Cuffe: 'Surprisingly, we both [turned out to be] fairly timid and wary of saying the wrong thing,' Emily says. Photograph: David Yeo for the Guardian

I find it easier to communicate with people through text than through speech and eye contact – I have more time to think of responses, and I don't run the risk of stumbling over my words as I often do when I'm nervous.

Tom and I met through posting on the online comments section of the Guardian website. We shared leftwing views on a variety of subjects and had a mutual interest in physics. We both came across as confident and, on occasion, slightly ill-mannered, when met with disagreement from others. I even thought Tom might be a professional astrophysicist, rather than another sixth-former armed with A-level physics and easy access to Wikipedia. As they say, you can pretend to be anything you like on the internet, provided you can write skilfully.

We were introduced to each other in an ideas and suggestions thread by a mutual online acquaintance, who had noticed that we had similar personalities and suggested we should write an article about how to get more people our age interested in politics. That didn't happen, but we exchanged contact details for an instant messaging service – communicating through email feels very formal to children of the 90s; it's far easier to get a sense of someone's personality over Skype and MSN.

Surprisingly, we were both met with someone fairly timid and wary of saying the wrong thing. We had regressed back to the small-talk stage: we knew how each other felt about the finer points of clinical trial methodology or Nick Clegg's Alarm Clock Britain, but we didn't have the slightest clue about favourite colours or films.

Thankfully, this was just a phase, but it took us a considerable time to admit that we were attracted to each other – it's far easier to be rude to someone via long-distance communication than it is to admit to love. Unfortunate, but true.

Several months down the line, and with far too much money spent on long-distance train tickets, we're still together. In February, I developed a currently undiagnosed illness with erratic symptoms that limit my ability to work, attend college and socialise for more than a few hours. It speaks volumes about Tom's strength that he has provided near-endless reserves of support during this time and I know things have been far less grim for it.

The internet is a lifeline for many long-distance couples, and especially for us, bringing a ray of light into an otherwise gloomy day. It's impossible to put a value on that kind of daily interaction and care. All I can say for sure is that it means the world to both of us. I'm sure my favourite astrophysicist can clarify exactly which world I'm talking about.

Second Life: Kristen Sweet, fell for her husband Steve, 52, as an avatar

Kristen Stewart, husband Steve and children: ''People ask if I was nervous about meeting someone from the internet, but I knew him so well by then I could gauge his mood from his typing.' Photograph: David Yeo for the Guardian

Second Life is a virtual world: you can go dancing, waterskiing, chat with friends – pretty much anything you can do in real life, only online. I signed up because I'd heard Duran Duran were giving a virtual concert and I'm a big fan. I created an avatar, Kira, and started hanging around with other fans on an island called Avalon, waiting for the band to show up. When Steve's avatar, Nic, turned up one day, I thought it might be Mr Rhodes himself, so I went up to ask him and we got chatting from there.

Some people make their avatars look like them, but I didn't. Kira was slim, blond and gorgeous; Nic tall, dark and handsome. We'd talk for hours, watching our avatars together while we typed away. Sometimes we went on "dates": you can teleport to various locations, so we'd go to a bar or club; we even went to the Titanic and had a look around. We had lots of mutual friends on Avalon, it was a party atmosphere; they'd stream music and we'd dance and chat. It sounds stupid, but it was like a night out without going out. You submerge yourself in this other world.

I had been in a controlling relationship and hadn't been out with friends for about 10 years, so Second Life was my social life. I'd go on every evening after my son, Sam, was in bed and be on there until 3 or 4am. Steve and I started instant messaging each other, then talking on the phone – he was in a long-term relationship, but he wasn't happy.

He lived in Plymouth and I was in Nuneaton, but in Second Life we were able to move in together after a month. We bought some land to build a house (this costs real money). In November, Steve proposed – it was Nic proposing to Kira, but it felt as if we were engaged in real life.

My relationship had ended, and in January 2007, we arranged to meet in person. People ask if I was nervous about meeting someone from the internet, but I knew him so well by then I could gauge his mood from his typing. We'd even had some intimate moments – you get animation balls that you click on to dance, sky-dive, anything really, and there are intimate ones, too.

Steve was taller than I expected, and on the chubby side, but it wouldn't have mattered if he'd had one eye – I'd already fallen in love with his personality. He spent the weekend with me, went home to tell his partner he'd met someone else, and within two weeks he'd put his house on the market and moved in. It hit us both like a steamroller.

We carried on meeting up in Second Life. We'd be in the same room, on separate settees, typing to each other's avatars. We still enjoyed the game and had friends on there – I make music and I even did a couple of virtual gigs.

On 10 May 2007, we got married in Second Life. I've got a friend in Nuneaton on Second Life, so she was my bridesmaid, along with two online friends from Germany and Scotland. My brother goes on there, too, so he was Steve's best man, and my mum logged on so she could come along.

A year to the day later, we got married in real life. Since then we've had two children: Kira, who is four, and Harry, three. The children know how we met, as do our family and friends. Some of our Second Life friends have even followed our lead and got married in real life, too. You get closer more quickly if you meet online, because of all the talking.

We still go on Second Life: Kira is a brunette now and I've changed Nic to look more like Johnny Depp. I think of them as separate characters, but Steve and I say it's as if Nic and Kira are still in there, and we're just the by-product of them meeting. When we log off, they're probably out there partying somewhere.

Myspace: Richard Cardenas, 33, cyber-flirted with wife Desiree, 28

I joined Myspace because a friend told me it was a good way to stay in touch. I never thought I'd meet anyone. I spotted Desiree's profile on a group for anime fans and sent her a message – something like, "Hey, maybe we should chat?" – as I often did to make new friends online. I assumed we'd just speak about anime, but little by little our messages became more personal. Perhaps it was because we were online and not face to face that I found myself telling her things I'd never told anyone before – not even my best friend. It was amazing how easily we opened up to each other.

In our sixth message, we exchanged pictures and luckily she liked what she saw. Gradually, our messages became more flirtatious – never suggestive, but definitely flirty. In June we arranged to meet up. Unlike other people I'd met from the internet, I never had any doubt that Desiree would be just the same offline as she was online. We ended up spending two hours with each other that day and had a great time. We started seeing each other seriously, and I proposed to her after just seven months.

Myspace wasn't mentioned at our wedding – Desiree's family are quite traditional and they would have found it uncomfortable. We told them that we met by chance.

On Valentine's Day this year, Desiree opened her Myspace account and we went back through our early messages. It was amazing to see the exact words we'd used when we first met – who else gets the chance to do that? I could see when I'd said something silly (like calling myself an overweight Mexican), or when I was bragging. It was fun and reminded me of why I'd fallen in love with Desiree in the first place.

I feel so proud of our relationship. We met online in 2004 and in 2012 we're still together, married, with three beautiful children. People say online relationships don't last, but we bucked the trend.

Twitter: Sam Pinney, 31, popped up in the timeline of girlfriend Katherine Wheatley, 30

Sam Pinney and Katherine Wheatley: 'Lots of people meet over the internet, but there's still a bit of a social stigma around it,' says Sam. Photograph: David Yeo for the Guardian

Like most people, I know that Twitter is for making X Factor jokes and talking about snow; a personalised news stream of the people and things you are interested in. It's not for finding love.

But I do have a habit of meeting people through the internet. I grew up in rural Devon and made friends through magazine chatrooms. No one turned out to be weird. Later, when my blog started to take off, I emailed a magazine to ask for a job and got one. These days, most of my social circle are people I meet on Twitter. It's like eavesdropping at a dinner party full of witty, interesting people – and being allowed to join in. Since you're generally tweeting about what you're up to in the day, if someone happens to be nearby, it's easy to meet up and say hello.

Katherine and I shared a mutual friend on Twitter, and I spotted her name on a group tweet. I thought she seemed funny, so I followed her. My first tweet to Katherine, an incredulous, "You like Tron?" may not be a classic start to a relationship, but it was enough to begin a gradual back-and-forth of heckling, talking about gin and exchanging pictures of tapirs. I didn't really think we'd meet. I assumed Katherine would just be another person on Twitter who made me smile.

A month later, I found myself at a loose end after a bad internet date had ended early. I tweeted that I was in Soho and Katherine replied to say she was only a street away, killing time before a wedding. We arranged to meet for a drink. The first time I saw her she was standing at the entrance to Great Portland Street tube station in a long red floaty dress and a little hat. It was a good first impression.

You're always a bit nervous when you meet someone from the internet, but Katherine and I hit it off immediately. Not long after that, she went to work in America for a month and we used Twitter to stay in touch while she was away. It's amazing how regular Twitter updates – however mundane – can make you feel closer to someone.

I was so excited about Katherine's return from America that I booked the morning off work and surprised her at the airport with flowers and a bottle of milk so she could have a proper cup of tea when she got home.

A year later, we're living together. When people ask how we met, we usually say through a mutual friend. It's weird, because lots of people meet over the internet, but there's still a bit of a social stigma around it – somehow it's better to meet someone in a grotty nightclub while drunk.

Maybe I should be more Twitter proud. I've landed myself a job, friends and a girlfriend all through cyberspace, and it would be ridiculous to pretend otherwise.

MSN: Daniel Miller, 24, and wife Jamie, 23, were modern-day penpals

I was 15, about to do my GCSEs, in Romford, Essex, when I first got a message from Jamie. She was 14, lived in a city called Springville in Utah, and wanted a penpal. In those days, when you set up a Hotmail account you created an MSN profile, with a photo and a little blurb about yourself. Jamie had gone through MSN profiles in England and contacted three girls and three boys. I was the only one who replied.

At the time, the only thing I knew about Utah was that it had funny Mormon people who had more than one wife. I've since learned that isn't true, but Jamie's upbringing sounded very devout and sheltered. She was completely different from the girls I knew or had been out with. She was more of an introvert. She struck me as having more morals than most girls in England.

I don't know if we'd have got to know each other so well if it had been just over email, but because we were able to talk through instant messenger, we could still have that real-time relationship. It's not the same getting an email and then waiting a few days to see if you get a reply. And the meaning of what you're saying goes over a lot better on an instant message.

At this stage we were just friends, but you feel more confident because you've got that third wall: you haven't met them, so you can say things you wouldn't say face to face. You're willing to reveal yourself a little bit more.

In April 2006, I spent three weeks with Jamie in the US. It was then that she became my girlfriend and, in August 2007, I moved to Las Vegas, to study at the University of Nevada. We've lived here ever since; I work in insurance and Jamie's a blackjack dealer for a casino.

People often ask us how we met, because I'm from England, and when I say we met online, they automatically think it must have been on a dating site. But I always say, no – we didn't go looking for love. It was a penpal relationship that blossomed.

Facebook: Angela Nolan, 37, met her husband Liam Adcock, 29, a few months after joining the site

Angela Nolan and husband Liam Adcock: 'I joined Facebook only a few months before I met Liam, to stay in touch with friends abroad – I didn't set out to meet someone online.' Photograph: David Yeo for the Guardian

We're both massive rugby fans. In January 2008, I posted a comment on the Ireland rugby team's Facebook page, and Liam replied. I was living in Shannon, Ireland, and he lived near Leicester, so he was an England fan; he supports the Leicester Tigers and my family are all Munster supporters.

We started off chatting about rugby and then he added me as a friend. I had a look at his picture – he's very attractive. We were talking online and on the phone every day and, after a few weeks, I told him I would be travelling to Birmingham for work. It was a lie, but I wanted to meet him.

I'd never met anyone online before and when I arrived at East Midlands airport, I did have a moment of thinking, "What am I doing?" But I think all along I just knew. We got engaged three weeks later.

I was 34, I'd been single a lot, and you go through those feelings of, "When's it going to be my turn?" I thought I might meet someone in a nightclub or locally.

I joined Facebook only a few months before I met Liam, to stay in touch with friends abroad – I didn't set out to meet someone online.

But I think it worked better because we met that way. We didn't go out on a first date and we had to spend solid time together because I was in another country. We spent a year flying backwards and forwards, and it meant we looked forward to seeing each other.

In April 2009, Liam handed in his notice at work and moved to Ireland. We got married on 16 October that year and it was during the wedding speeches that my father found out we'd met on Facebook.

I think it was fate that we found each other online. In his speech at our wedding, my best friend said there were three words that came up when he thought of the two of us: I just knew. That's how I felt, too.

• Interviews by Charlotte Northedge and Becky Barnicoat