The REAL reasons people cheat: I’m a psychotherapist who spent five years researching affairs. This is what I discovered about the signs people will stray – and why it’s all routed in your childhood: JULIET ROSENFELD

In June 2021 Juliet Rosenfeld placed a classified ad in a handful of respectable publications asking: ‘Have you had an affair?’

Within days the leading psychotherapist and writer had received scores of replies, ranging from the familiar to the bizarre.

The result is Affairs, a book that Rosenfeld intended to write in a year but which was so complex it took five. It is the book of 2025. It involved hundreds of hours of research and interviews and tells the story of five affairs in shocking intimacy. One successful man, called Neil, is addicted to younger, vulnerable women (see below); a psychotherapist seduced her patient; a married woman had a sexual relationship with her female colleague (if you missed the extract in yesterday’s paper, you can find it on mailonline); a mother of four fell in love with the husband of a tennis club acquaintance; and a doctor is entirely emotionally dependent on an online affair with a dominant married woman he calls Goddess.

I found it brutal, heartbreaking and, in a strange way (after its tales had settled in me), inspiring.

‘For many people, affairs are as hardwired in their DNA as fidelity,’ writes Rosenfeld in the book. ‘What’s rarely understood is that the roots of most affairs are there decades before two people meet. Yes, decades. The reasons are locked in our infancy and childhood. That is, in the past not the present.’ 

Affairs are meat and drink to psychologists. Rosenfeld says polling shows that one in five British people say they have had an affair. (I suspect it is more. It is not unknown for people to lie to pollsters.)

‘Seeing otherwise sensible people misbehave is one of the reasons why affairs are so fascinating to onlookers. Especially when sex is involved,’ continues Rosenfeld. ‘These stories remind us of our own potential to do things we shouldn’t. Who has not fantasised about sex with someone who is not a partner?’

She adds, ‘I cannot emphasise enough that the central motivations for affairs relate to our own infantile, forgotten selves. Without adequate caregiving and interest early on, we try to seek emotional and physical reassurance and stimulation in a myriad ways throughout life. Having an affair is one way.’

I meet Rosenfeld in her consulting room in central London on a cloudy day. It is small, high-up like an eyrie and oppressively quiet.

It has to be: this is the silence where you hear yourself. Rosenfeld is 56, dark-haired and slender; nervous, I think – she is not used to talking about herself – and warm. She’s been a therapist for 20 years, having studied at Oxford then worked in advertising, and briefly the civil service, before retraining. 

I have a kind of nauseous flashback: I spent time in similar consulting rooms in central London, years ago, when I was treated for youthful alcoholism. But I am not a patient, and neither are the people in Affairs. They did not come to Rosenfeld for treatment but to tell the truth and provide insights and clues into infidelity.

‘We have all felt rejection at some point,’ Rosenfeld tells me. ‘We’ve all wondered what was going on behind a closed bedroom door. How can you not be interested in relationships? It’s the stuff of life, isn’t it?’

In Affairs Rosenfeld is keen to spell out that our past, from babyhood onwards, can provide clues as to whether we will have an affair: ‘I want to show how otherwise reliable, sensible, kind, loving, thoughtful individuals can become selfish, sexually obsessed risk-takers. Common sense vanishes, jeopardy triumphs. Two people involved in an affair often believe they are “star-crossed lovers” or it was “meant to be”, but this is fantasy.’

After realising that asking acquaintances about their affairs for her book would be impossible, a journalist friend suggested she place an advert on Mumsnet, in The Spectator and both The London and New York Review of Books. Having whittled down the candidates to five, she interviewed them over Zoom, sometimes several times a week, often with long gaps due to their life circumstances, and usually with the camera off.

When I read Affairs, I initially felt rage: adultery is the fiend of marriage. But Rosenfeld listens so hard – you feel you can hear her listening – the characters make sense. Often, they behave appallingly.

But as their stories spool out, you begin to understand and your heart breaks for them – even Neil, who it turns out was abandoned as a child and remembers as a boy hearing his mother having sex with other men in her bedroom when she thought he was asleep.

‘Some people seem to need to have a “third” in order to move out of an unhappy relationship. They can’t just say, “Right, this relationship is not working. I’m leaving”,’ says Rosenfeld. But, as she stresses, the roots of all our adult relationships are laid down in childhood. ‘One of the first things you learn when you do couples-therapy training is that an affair is a cry for help – when all else has failed. This book is about people desperately trying to seek a solution.’

She believes that Neil has been fighting off having a breakdown, probably since childhood. She calls some affairs – Neil’s particularly – ‘scaffolding’ for the mind, an attempt to repair or support vulnerable aspects of the self, to stop it from falling down. ‘Very often’, she adds, ‘the reason someone has an affair has nothing to do with their partner. It predates meeting their partner.’

So how do we avoid affairs? ‘You stay in your couple by knowing yourself as well as you possibly can,’ says Rosenfeld. ‘And by being able to have arguments that may feel relationship-ending. You sustain marriage by all the things that we know: being kind, understanding, patient, tolerant. But it’s also about knowing yourself really well, and that means quite a lot of the work needs to have been done separately. You can’t rely on a partner to do the psychological heavy-lifting for you, particularly of one’s childhood.’

I tell her that’s a dagger through my heart. (I am joking, but only partly.) The fantasy of marriage, of ‘the one’, is that your partner will save you, so you do not need to save yourself – the Disney promise.

‘It’s a dagger through all of our hearts,’ she replies. ‘Freud had this brilliant thing. He wouldn’t work with patients who were in love because he said they were psychotic. He said, “You can’t reason with them.” Love puts you in a strange place but it’s not sustainable. You have to be able to move out of passionate absorption into something more mature.’ And if you have this – or can learn it – you will ‘come together, separate, come together again and really confront difficult things without one person being the nurse or the doctor for the other person’. She adds, ‘That never works.’

Because marriage is ‘Till death do us part. If you’re going to survive that, you have to be very truthful about unhappiness and anger and about the origin: that sometimes it is in you, it’s not necessarily in the other person.’

She says she wrote Affairs, ‘because people see a psychotherapist when a solution falls apart. All these people had found an affair as a solution, and when the solution broke, they tried, more or less unsuccessfully, to get help. But if an affair can be overcome, then sometimes you have the roots of something really strong in your relationship. It requires so much work, though, and forgiveness.’

She says she found the interviews intense. ‘Often, I felt very moved by what I was hearing. Sometimes I felt distaste. Sometimes I felt a bit intrusive, and I had to manage that and retain my impartiality. I feel a lot of debts and responsibility. And I hope I did right by people. I did find it awkward sometimes, listening to people telling me these incredibly private, secret feelings when I wasn’t their therapist, I wasn’t their friend, just a sort of voice.’

Her response to her subjects was the same as mine: ‘The bits about sex had much less impact on me than listening to someone explaining how they had betrayed someone who trusted them. That was hard.’

Affairs is Rosenfeld’s second book. Her first was The State of Disbelief, a tract on grief after her husband of less than one year, Andrew Rosenfeld, died of cancer in 2015, aged 52. ‘By the time I’d written this book my life was back on an even keel,’ she says. She has married again (her third marriage – she has two boys, 19 and 17, from her first), and the book is dedicated to her current husband, Luiz. 

But she pauses. ‘I think all of this is suffused with loss. There are obviously lots of joyful bits in most people’s lives, but I think everybody’s lives are embroidered with loss. There’s loss everywhere, and the loss of an actual person, the dematerialisation of a body, is unlike any other. But the loss of love and trust has its own kind of horror.’

I ask about endings. The only real tragedy among her five adulterers is Neil, but there are people who seemingly can’t get better and I can only hope that his wife never finds out. Rosenfeld tells me how she saw him once, after she’d finished researching the book, sitting in a café in London’s Marylebone with a younger woman. She noticed he was touching her, and, she wrote, ‘He had his shin up hard against her long calf.’ This made me shudder.

I ask Rosenfeld what Freud thought about adultery. She says without hesitation, ‘Freud said when we lie, we get sick. He said that keeping secrets requires tremendous psychical energy that eventually drags a person down. The greater the lack of honesty with which you can live, the greater the toll on the body.’

So our adulterous neighbours, often envied as the gilded and the sensual, are some of the loneliest people there are. I pity them now.

Affairs by Juliet Rosenfeld will be published by Pan Macmillan, price £20, on 27 March. To pre-order a copy for £17 until 7 April, go to mailshop.co.uk/books or call 020 3176 2937. Free UK delivery on orders over £25 

All names have been changed.