It is the perennial question with which women have tortured themselves since time immemorial: why, exactly, do men cheat? Why do seemingly supportive partners, who had all the hallmarks of loyal marriage material during the courtship period, become serial philanderers once the gold band is in place?
"It's simple," says Peadar De Burca, the playwright and comedian. "It's because they can. Or, rather, because you ladies let them think that they can. So they do."
Harsh words I hear you say. De Burca, however, has a wealth of research -- gleaned at the coalface -- to illustrate his assertion. He is not, one hastens to add, one of the aforementioned unfaithful (married to Wanda just one year and the proud father of three-month-old Lilly Lola).
Instead, he has spent the past five years teasing out doleful tales from 250 men who wander, and 60 women who have endured their husbands' dalliances.
From this Thursday, De Burca will present a comic monologue at the Edinburgh Fringe entitled: Why Men Cheat, an uproarious and, at times, poignant show that lays bare the aims and origins of male infidelity. The show has been staged successfully here in Ireland for the best part of five years.
"Sadly, my conclusion has been that, all too often women simply won't challenge their cheating men," he says with a shake of the head. "Or their self-esteem has been so battered by their husband's behaviour that these talented, attractive and intelligent women convince themselves that they have too much to lose if they walk away or show him the door."
De Burca is a comedy writer who originally found success as a playwright adapting popular films for the stage, including Quentin Tarantino's Reservoir Dogs and Pulp Fiction, as well as When Harry Met Sally and Chitty Chitty Bang Bang.
The author comes from a long line of philanderers, and has a healthy respect for monogamy.
But he became fascinated by the subject when it ripped apart marriages within his own family circle.
"Witnessing the pain some of my female relatives suffered was heartbreaking. The effect was that, from early on, I swore I was never going to become one of those men."
So he set out to investigate the subject, amassing a wealth of hilarious though thought-provoking stories from men who cheat.
Encouraging philanderers to spill the beans wasn't much of a challenge, he says. "Get men to talk about their extramarital exploits? Get them not to talk would be harder," he says.
"Never underestimate the male ego. Men just love to boast of their conquests. Call out the word 'cheat' on any street and a dozen guilty men will look furtively over their shoulder.
'Yet of the women I spoke to, all but three forgave their husbands and took them back. Which was, of course, a green light to the men. My advice to women? Show your confidence. Let him know he's lucky to have you. And that if he abuses your trust, he's out."
"He told her that he had found solace elsewhere because she had become cold, sex was no longer as regular as it once was, and he had found affection elsewhere. He came back to me saying she now felt so guilty that she kept apologising to him. You can't believe how arrogant he was about it. And, of course, it was carte blanche to continue.''
Another of De Burca's interviewees, a business executive with a big bank balance but few social graces and little in the way of good looks, said he had juggled eight mistresses and made weekly visits to swingers' parties.
"I found it hard to get under his skin," De Burca admits. "I couldn't pin him down as to why he needed to do all this cheating. Eventually, he lost his rag and he blurted out: 'Look I cheat. I have to. Otherwise I'm dead.'"