If any couple can be credited with pulling their marriage back from the brink, it’s surely Tal and Samara Araim. After 16 years and with two children together, Tal embarked on an all-consuming affair with one of Samara’s closest friends. It lasted two years, until Samara’s “oh-my-God moment” when suddenly, from nowhere, she knew. They separated immediately and didn’t speak for months. Samara wiped Tal’s number from her phone, changed her name on her email account and all communication was through lawyers. All the divorce papers were signed except one.

Fast-forward four years and here they are on a sofa talking openly, easily, lightly – and laughing a lot. Their journey has been so revelatory that Tal has not only written a book in an effort to share all he has learned, but also turned their former family home in Surbiton, south-west London, into a therapy centre, Compass4Couples. Downstairs is a lecture space that hosts free seminars and workshops. Upstairs, qualified counsellors provide individual therapy.

Tal is a man on a mission – his vision is a kind of “relationship gym”, not for couples in crisis but for those who are ticking along. “We have hospitals where you go when you’ve had a heart attack and gyms where you go to stay healthy,” he says. “With marriage, we only have the hospitals – we look for help when it’s almost too late. If Samara and I had gone somewhere like this at the beginning, the whole thing might never have happened – because, honestly, when I look at our ‘issues’, they weren’t that major.”

It’s true that, in many ways, their marriage does seem to have fallen into familiar traps. Both from Iraqi families, they met at a wedding when Samara was an art student, and Tal, at 30, had just opened a restaurant. The first thing he noticed were her eyes and her lips – and he promptly asked Samara to come to his restaurant and change the logo when in truth, he admits, “it didn’t need changing!”

For Samara, Tal was different to anyone she’d ever dated. “I was only 18 and, until then, everyone I’d been out with had been a teenager. Tal was a proper man who knew what he wanted. I loved that.”

Three years on, they married and by her mid-20s Samara was at home with two young daughters – the only one of her friends to be at this stage. Meanwhile, Tal worked long hours at his restaurant. “We stopped being friends,” says Samara. “We were parents, partners – but not friends. We stopped doing things for us or going out as a couple. Life became a routine and everything was about the family – never me and him.”

Tal agrees. “Samara might call me at the restaurant and I’d say: ‘What? I’m busy. Is it important?’ I could be working out the price of a dish, selling a Christmas party to some company – and I knew Samara wouldn’t be calling to put a smile on my face. It would be: ‘The light doesn’t work. What’s the electrician’s number?’ Everything had become functional. That’s the point where we needed help.”

If there was a catalyst for the affair, Samara and Tal agree it was the closure of the restaurant when the lease ran out. “By then, I’d started a property company, which produced 80% of our income, so when I closed the restaurant that became my job,” says Tal. “That restaurant had been me: I’d go there, I was on stage, I made people happy. Property? I had zero passion for that. Then, at the same time, someone starts to pamper my ego and tell me I’m great. I’m not blaming anybody. I’m an adult and it’s totally my fault but it was exactly what I needed to hear.”

This somebody was one half of a couple who had become close friends with both of them. The two couples went on holidays together and would meet for dinner or drinks two or three times a week. Though the other couple had no children, they were close to Tal and Samara’s daughters. They were a regular fixture of their family life.

“There’s no denying there was a void somewhere and now it was being filled,” says Tal. “At the beginning, it was exciting. She’s reading the books I’m interested in and then she gives me the book she loves and I read that. She tells me I’m so funny, that I’ve got a great voice! I know it’s shallow, but it’s the seductive power of acceptance.”

And how important was the sex? “Not very. To be honest, you don’t stay that close to someone for two years just for the sex. By the latter stages, it was something I had to do so we could have lunch and talk. I have to keep telling myself that I never paid a gas bill with this woman or fought about the in-laws. We didn’t do anything real. What I enjoyed was the mental connection. For a while, I glorified this woman.”

Did he feel guilty? “Absolutely! I’d come home, go to the bathroom and cry. It’s messy. It’s not fun.” In fact, not surprisingly, the double life took its toll. “The more I struggled, the more I had to hide it from everyone – even the person I was having the affair with. I tried to recreate the fun side. It meant I wasn’t showing anyone what I was feeling and, in the end, it was just too much.”

By then, Samara knew something was wrong. Tal was distant and unhappy, often saying that the marriage hadn’t worked and he wanted a new life, but never telling the whole truth.

“I’d suspected an affair but he’d denied it,” says Samara. “Suddenly, for no reason, the whole puzzle made sense and I said to Tal: ‘I’ve just realised what’s been happening …’ Straight away, he told me I was right. To this day, I think what an idiot I was. How could I not have guessed? I was so naive, so trusting. This couple were in our house a lot. I thought she was my friend. I felt so betrayed. I told Tal to get out of the house as I never wanted to see him again.”

Tal’s marriage was ending – and so was his affair. “I was losing my children and this woman used an expression like ‘this is your problem, not mine,’” he recalls. “That was the wake-up call. I was ruining my children’s lives and it didn’t even affect her? Oh my God. Had I really been that dumb?”

He began therapy, which provided crucial insight into where he had gone wrong and what he wanted – and that was his family. “I wanted my children and I missed Samara,” he says. “I realised she was the one who had been there with me when it counted. She was always on my side against my family or the restaurant manager or the bank manager. I missed her because she was my friend. I wanted one last chance.”

Somehow, he persuaded Samara to start talking. She began therapy, too, first on her own, and then with Tal.

“The betrayal had been so terrible, I needed some help,” she says. “It was also for the kids – what had we done to them? We weren’t good at breaking up – I was angry and hurt and we’d done everything a divorcing couple shouldn’t do. I wanted to deal with this in the best possible way.”

Reconciliation was slow – it took two years before they lived together again. “We had to see it as a new relationship,” says Tal. “I wasn’t going to be the same person. We really had to start again. We went on dates, the odd trip. Then I’d stay over. It was building something that was honest and relaxed, with silliness and laughter.”

They’ve tried to be completely open with their daughters, now 13 and 15. “We talked about everything,” says Samara. “Nothing is taboo. At one point, our youngest got very angry with Tal and I told her to ask him all the questions she had, which she did.”

“Maybe I’m being delusional but I hope we’ve taught them there’s no such thing as perfection,” says Tal. “That magical picture of role-model dad or mum doesn’t exist. There’s no such thing. We all make mistakes. It’s how you deal with them.”

Neither Tal nor Samara are pretending this is a straightforward happy-ever-after. “Deep down, though I tried really hard not to, I still loved Tal. I’d been with him since I was 18, a huge chunk of my life. You’ll never forget what happened – it’s like a scar that will always be there for all of us,” says Samara. “But it’s healing. You accept what has happened and move on to something better.”

Although Samara is not involved with the Compass4Couples centre, she is right behind it. “Getting married is a bit like having a baby – you bring it home and what do you do next? There’s no one to teach you about being a couple. You forget, after a while. You make an effort with friends, family, children – but your partner’s just ‘there’.”

Tal says: “Samara and I are silly together now. We laugh, we’re playful. I think we should have relationship gyms everywhere, somewhere you can go to access the research, make sure you’re not beginning bad habits.

“Maybe it’s wrong to say it but I think in the end, we’re in a better place. The best time of our relationship, honestly, is today. I wish we hadn’t had to go through all that to get here – but in the end, we’re in a better place.”

• The Coupledom Trap by Tal Araim is published by Filament Publishing, £8.95.