Denise Knowles, a sex and relationship therapist with the charity Relate, says patients often say to her: “There are so many options, I don’t know where to start.” Thirty years ago, Knowles was mostly approached with physical problems: erectile dysfunction, painful intercourse, issues with ejaculation. Now she describes the scope of her work as “bio-psycho-social”. That is to say, everything has got a lot more complicated.

“I think it has gone from being very much: ‘This is the problem; this is how we resolve it,’ to: ‘How do we approach sex? What does it mean to you? How does it fit into the relationship, and how have you got to this place?’” She laughs. “Then we can start to deal with it.”

When Dan Savage started out as a sex advice columnist, he used to regularly get asked: “Where is my local swingers’ club?” Now every swingers’ club has a website, he says. There has been one other big change in his inbox since 1991, when his advice column, Savage Love, first appeared in the Seattle newspaper the Stranger: the near-disappearance of the question: “Is this normal?” It used to make every other letter. “I think it’s got through to people that, when it comes to human sexuality, variance is the norm.”

It is true, as Savage says, that there is greater recognition that what might once have been thought of as archetypal sex – within a heterosexual marriage, probably in the missionary position – “is actually the minority of sex that goes on”. But even that awareness has brought with it concerns.

“People compare themselves with what their friends, media and society say or seem to expect, even if it is untrue or unrealistic,” says the Guardian’s sex advice therapist, Pamela Stephenson Connolly. There has never before been more varied discussions of not just sex, but everything that goes with it: gender, identity, relationships, love. Yet this has not necessarily translated into less shame – or even more open communication.

For many, says Knowles, the result is a kind of paralysis. “There are all sorts of small doubts creeping into people’s minds about what it is to be sexual, and even how.” Throw in expectations warped by pornography and social media, and distractions from phones, and sex therapists say their books have never been fuller and their clients never younger. “Every psychosexual therapist I speak to has a full waiting list,” says Kate Moyle, a therapist in London whose clients are mostly in their 20s and 30s.

The increase in young men seeking help with erectile dysfunction (ED) is especially remarkable. “I’ve never seen so many young people walking through the door with real concerns about their ability to orgasm,” says Caroline Lovett, who has worked in sexual health support for 35 years, primarily as a nurse.

Whereas ED was once associated with health problems in older men, it is now far more common as a psychological issue in younger ones. “What we’re finding is a generation of men who find it much easier to have a sexual relationship with their device than a person,” says Lovett. Like other therapists I spoke to, she says the prevalence of pornography is at least partly to blame.

A 2016 Relate study found that just over half of its counsellors reported seeing an increasing number of clients where pornography was causing a problem in their relationship. Almost a quarter said the same of clients with sexual problems such as ED.

The sex therapist Nicola Buchanan decided to specialise in sex addiction in response to the number of men coming to her with ED and other issues relating to online stimulus. She says the shift from masturbatory fantasy to sexual reality has “always been a transition that people have had to go through – but these days it’s just such a jump”.

For young women, Lovett sees the impact of pornography in their expectation that they orgasm “in about 10 seconds flat”, body image insecurity and even dysmorphia, and a preoccupation with their partner’s pleasure. Many told her that they had felt pressured to have anal sex. Other therapists reported an increase in women with vaginismus, where involuntary muscle contraction prevents penetration, which they linked to anxiety.

Sexual healing … Kate Moyle, Dan Savage and Pamela Stephenson Connolly. Composite: Jean Goldsmith/The Observer; Jeff Vespa/WireImage; Tracey Nearmy/AAP/PA Images

In her 2010 review on the sexualisation of young people, the psychologist Dr Linda Papadopoulos found that “girls and boys were under pressure to emulate polarised gender stereotypes”, with the impact particularly profound on young women.

Dating apps have created the impression of limitless choice, leading some people to overestimate their attractiveness, says Papadopoulos. “You wouldn’t walk into a club and go: ‘I have a chance with everybody here,’ but with these apps you do, or you think you do.”

Since apps went mainstream, Stephenson Connolly says she has received questions that show people “expect to be able to bypass courtship behaviour”, which may stymie their chances of finding a connection.

Cate Mackenzie, a dating coach and sex therapist with 20 years’ experience, says there is increasing recognition of “sexual privilege”: the difference between people who “can just meet people”, and those who, for a range of reasons, might reach their 30s or 40s never having had sex. She teaches clients how to flirt and relax into a conversation.

But that is a struggle even within relationships. Most sex is over within 10 or 20 minutes, says Moyle, but even that is proving too much for fractured attention spans: “You have to switch off to turn on – and we never switch off.” Many therapists say their work begins by barring technology from the bedroom and enforcing shared bedtimes – “Really, what I’d consider fairly sensible things,” says Buchanan.

“If the first thing you stroke in the morning is a device, that’s probably quite telling,” says Lovett, adding that she has seen an increase in affairs facilitated – and discovered – through technology. A surprising number of her patients admit to digitally (and illegally) tracking their partner without their knowledge.

Buchanan says she sees young people who have never managed to have relationships at all: “I think maybe the lifestyle we live isn’t conducive to couple relationships.”

Savage is a longtime sceptic of monogamous relationships, particularly as a path to long-term sex. “People expect of their partner what they used to get from many people – their support, best friend, therapist, sex partner. A relationship can’t bear the strain of all those responsibilities.” Based on his mailbag, Savage says there has been “cross-pollination between gay and straight lands” over the past 30 years, resulting in a more pragmatic, user-friendly approach to sex. He points to the embrace of casual relationships and safe sex for pleasure, and the trend towards settling down only after “sampling the platter”. Fewer people are in relationships they don’t want to be in, he says.

In the US, divorce in adults aged 50-plus has doubled since the 1990s; for over-60s in the UK, it has increased by roughly 70% since 1991. Back then, says Stephenson Connolly, ageism about sex was more common, while today she receives letters from people in their 80s and 90s. “People generally have higher expectations now that they should enjoy sex well into old age – a terrific advancement.”

The arrival of pharmacological solutions has played a part, though she still receives many requests for help from women responding to hormonal changes. “But rather than giving up, they are expecting solutions and relief – another positive change.”

For all the talk of lifting stigmas, therapists say uniformly that, for many people – even the majority – sex remains a taboo. Moyle points out that society is still predominantly heteronormative and kinks are not openly discussed. “We’re in this really weird paradox where everybody looks like they are having sex and is talking about sex, but the realistic, normal conversations are not happening.”

Even at the individual level, Lovett says conversations today are no more frank or open than they were in the mid-1980s. Buchanan finds there are more barriers than there were 15 years ago. “A bit of me is still surprised by people’s ignorance around their own bodies and their partner’s,” says Knowles. More pragmatic, robust sexual education is sorely needed.

People’s readiness to seek qualified advice, though, is a positive step. “I believe generally there is an increased awareness regarding the work of sex therapists and the possibility to receive help,” says Stephenson Connolly. Fully booked sex therapists could indicate a societal crisis over sex – or the desire to get to grips with it. People pursuing sex therapy are investing in their health and happiness, and that of their future partners, says Moyle: “It’s really positive that people are recognising it before they get stuck.” Lovett says therapists tend to be approached about problems on average seven years after they originated: “If I see somebody early on, it’s a blessing.”