This week, after 26 years of marriage, LibDem MP Chris Huhne admitted he’d been having an affair. So why do men cheat? Playwright PEADAR DE BURCA, 36, who is married with a baby daughter, has spent five years interviewing 250 adulterous men. Here, he tells TESSA CUNNINGHAM the secrets cheating men would rather we didn’t know... Teresa had been suspicious of her husband for weeks, but as she sat in her car watching him walk into the home of an attractive blonde, she was stunned. Nick was a GP, but this was no ordinary house visit. For starters, he was off duty and had told Teresa he’d be at the gym.

Her heart was hammering as she marched up to the front door. It was opened by a red-faced, flustered young woman. Teresa pushed her to one side. ‘I know my husband’s here,’ she snapped, as she stormed inside and marched from room to room.

She hurled open the door of the airing cupboard and there, crouching behind a pile of towels and sheets, was Nick. He was naked, except for his expensive designer glasses.

‘It’s not what it looks like. You are just imagining things. Please go home and everything will be OK,’ he said.

Welcome to the world of cheating husbands. They tell the most outrageous lies, they have one mistress after another and - most amazing of all - they often get away with it.

While terribly hurt by her husband’s betrayal, Teresa decided to accept his grovelling apologies and take him back. They are still together and, yes, he is still cheating.

I come from a long line of cheating men. Several of my uncles were womanisers and it destroyed their families. Their wives were always at loggerheads with them and their children grew up insecure. Similarly, many of the lads I grew up with have turned into womanisers.

But I wanted to be different. I knew I wanted to settle down and find what seems elusive these days: a happy, committed, faithful marriage.

So five years ago I embarked on my quest to find out what makes men cheat. Are some men programmed to be unfaithful? Is it something in their DNA, an overdeveloped sex drive or irresistible charm?

What I discovered was much more shocking. After meeting hundreds of adulterers, I’m convinced they cheat because they can get away with it.

I talked to more than 250 men from all walks of life - doctors, dentists, lawyers, bankers, footballers, teachers and the odd millionaire.

All had cheated on their wives but, incredibly, only 40 of them had been found out. The others got away scot free and are still at it - as are many of the men who were found out and forgiven.

I also talked to 60 betrayed women. All except three have stuck with their cheating husbands.

When women don’t have the courage to stand up for themselves, it’s virtually a cheat’s charter.

I’ve been left ashamed by the dirty tricks my fellow men get up to and horrified by the way women let them get away with murder. Quite simply, women deserve better.

Take Teresa. Tall, blonde and witty, she lives in a stunning house outside London with her husband Nick. In their early 40s, they had been married 15 years and had three children when Teresa began to suspect things weren’t right.

Her husband was spending more time at the gym than usual. Yet when he came home, his kit was clean.

One evening, Teresa followed him - to his mistress’s home. ‘Even when I found him naked in the airing cupboard, he had the gall to try to persuade me it wasn’t as bad as it looked. He was so calm that I almost believed him,’ she says.

But even though she had caught him, Teresa decided to forgive him. ‘I have a lovely home and a great lifestyle. I don’t want to lose all that and see my children grow up without a father,’ she says.

‘And I don’t want to face life alone. Who would want me? I’ve stuck with Nick and he’s carried on cheating. I know he will never stop. Now I just turn a blind eye. I still love him, but I don’t trust him an inch.’

The betrayed wives all had one thing in common - a lack of confidence. They were at least as attractive as the mistresses and a great deal more intelligent. But they let their men walk all over them.

When I started my quest five years ago, I imagined it would be hard to find cheats and even more difficult to find ones willing to own up. I couldn’t have been more wrong.

Call out ‘Cheat’ in any street and a dozen guilty men will look furtively over their shoulders. My first cheat - who I met through a friend of a friend - flicked open his address book and it was a roll call of fellow philanderers. It takes a cheat to know one. They passed me on like a parcel. And they weren’t simply willing to open up, they were bursting to tell me all about their affairs. The male’s capacity to boast about his sexual prowess knows no bounds. Once they started reeling off their conquests, it was impossible to shut them up.

Aged from 25 to 65, some were handsome, some were downright ugly, but most were successful. I imagined they’d be living exciting, glamorous lives. But nothing could be further from the truth. If one thing’s certain, affairs don’t make you happy. Once I’d dug beneath the boasting and bravado, I was stunned by just how insecure most of these love cheats were. Most admitted they weren’t even driven by sex. They just wanted something to fill their empty lives.

One evening, my research took me to a bar, where I met a married man in his 30s and his girlfriend. Like most of the mistresses I met, she barely had two brain cells to rub together. A decade younger, she was obviously attracted by the money and didn’t seem to care whether he was married or not.

When she went to the ladies, the man passed me his mobile phone to show me photos of his children. ‘I love my family. I know I’m ruining everything, but I can’t help myself,’ he sobbed. He was so pathetic I almost felt sorry for him. But having spoken to all these men, I wonder if they’re capable of love — I’m not sure they even love themselves, so how can they love their wives? If they did, would they risk inflicting such pain on them? 

Until I started this project, I hadn’t realised how devastating it is for a woman to know her husband has been unfaithful. The wife of a serial cheat told me: ‘You see yourself for the first time through this unforgiving mirror. Suddenly every little fault and imperfection is exaggerated. ‘I used to feel good about myself because I thought I had a husband who loved me and was faithful. Now that’s all gone. Even though I know he’s to blame, I’ll never feel as good about myself again.’ You’d expect cheats to feel guilt, but, believe me, most don’t. The men I met seemed to find it impossible to understand the damage they had caused.

They seemed far more interested in their next affair. And when they were found out, they often turned the tables on their wives.

One man boasted to me: ‘When my wife discovered my affair, I managed to make her feel guilty. I told her it was because she’d been ignoring me and had gone off sex. In the end, she was the one apologising.’

I’m convinced part of the trouble is that we allow men to think philandering is harmless.

Look at the way we tolerate Bill Clinton. One of the saddest stories I heard was from a woman whose husband had cheated on her when their youngest child was seriously ill.

Desperately worried, this poor woman had started comfort eating and had put on weight.

When she discovered her husband was having an affair, even her own family suggested she was partly to blame. ‘You shouldn’t have let yourself go,’ they tutted.

It’s a cliché, but a lot of men start cheating when they hit middle age. They realise they’re never going to be David Beckham or Bill Gates, but they can have a fantasy life with another woman.

So, what can women do to protect themselves against cheats?

First, be wary of women with long hair. One of the most unexpected things I discovered was that men nearly always cheat with women who have longer hair than their wives.

I’m not a trained psychologist, but the reason couldn’t be more obvious — or more shallow. They want to rekindle their youth with a younger version of their wives and long hair seems to equal youth.

There was only one man for whom I felt any empathy or affection. And he was the only man who had an affair with a short-haired woman who was older than his wife.

Sean, a teacher, fell in love with Nuala, a widowed barrister, when they appeared in an amateur dramatic play together. At 57, she was 20 years older than him.

‘My wife and I had been drifting apart. Nuala was flirty, tactile and great fun,’ he says.‘At the aftershow party, we went out for a cigarette and ended up kissing. It was totally unexpected and I felt overwhelmed by guilt, but I couldn’t stop myself.

‘We drifted on for a year until my wife discovered us together and threw me out. I feel terrible for the pain I caused and wish I’d been brave enough to be honest about what I was doing.

‘My wife is in a new relationship and we are both much happier.’

Sean was the only man I met who fell in love with his mistress and was prepared to end his marriage. But even he tried to have his cake and eat it for a year.

The simple truth is that most cheats are cowards. They are not brave enough to admit there might be problems in their relationship.

Instead, they embark on affairs that involve secrecy. When they are caught out, it’s normally down to something as clichéd as lipstick on their collar or a scratch mark they can’t explain. And if their wife forgives them, they believe they’ve got carte blanche to carry on. I’ve met only one man who stopped cheating, even though he’d never been found out.

If his case wasn’t so tragic, it would be comical. Paul, a 46-year-old builder and a notorious womaniser, was having an affair with a neighbour when he developed narcolepsy. Every time he got excited, he fell asleep. The doctor put it down to stress. And no wonder: Paul had been leading a double life for 20 years. His mistress left him because he couldn’t perform any more. He lost his job and can’t even watch football, because he falls asleep as soon as things get exciting.

‘The worst part is that my wife is so sympathetic,’ he says. Having spent years trailing serial philanderers, I can’t believe why more women don’t read them the riot act. By and large, these men had fantastically attractive women at home who were prepared to be treated like dirt. And that’s the problem. If men think they can get away with cheating, they will. The secret to keeping your man faithful couldn’t be simpler: be confident, demand attention and make it clear he is lucky to have you and won’t get a second chance.

I’m also convinced there are faithful men out there. They have a moral code and strength of character. They don’t lie or cheat. They’re more interested in being the sort of father their children can look up to than their own selfish pleasure.

Am I that sort of man? I really hope so. Not just for my wife’s sake, but for mine. Most of the adulterers I met are the most miserable men on earth.