After pop star Ronan Keating's affair was exposed, his wronged wife Yvonne has come out and said something many other betrayed women have felt before her.
The reason she is finding it so hard to forgive him is that 'it wasn't just sex, it was emotional'.
In other words, a one-night stand is one thing - in time a woman can forgive a sexual betrayal - but a prolonged liaison is different. You see, if there's one thing a woman can't bear, it's having her emotional security threatened.
Interestingly, when it comes to divorce, the majority of men sue on the grounds of adultery - whereas women sue on the grounds of unreasonable behaviour.
Men can't stand the idea of another man laying claim to his woman's body, while women can't stand the idea of another woman laying claim to her man's heart.
What a woman really minds is discovering that her man is whispering sweet nothings to another woman and bestowing on them the kind of attention that he used to reserve for her.
Attention and affection is what a woman really wants, even if they've been married for ever. So the fact he's giving it out elsewhere is a betrayal amounting to high treason.
As an agony aunt, I receive letters from women who have discovered that their husbands have been having an affair. They almost always say that if it had just been a one-night stand, they could have forgiven it (we're all human).
But it's the length of the relationship and the betrayal involved they can't tolerate. As one woman put it: 'If he can lie straight to my face, day after day, for months, what else is he capable of?'
Again, it is not so much about the sex as the emotional attachment they care about: 'I don't think I can ever trust him again.'
Many women are terrified by their own responses. Would they ever be able to truly feel safe in the relationship again?
As a friend of mine said, after she had discovered her partner had been having an affair for years, not only did she feel like an idiot for not seeing it - and for trusting him completely - she was terrified that she would turn into a suspicious, jealous bitch (her word).
'I'd constantly want to punish him and I don't want to be that sort of person,' she said.
'I would end up not only hating him, but hating myself, too.'
At the same time, if a woman strays, it tends not to be for the lure of a pair of buff biceps and a six-pack, but because she is feeling ignored at home.
The letters I receive as an agony aunt from women secretly confessing to affairs are never about sex. They are, without exception, about their husband treating them like a piece of furniture.
'He doesn't even notice I exist,' is one complaint. The other (most common) is: 'He doesn't talk to me.'
So when the bloke in the office takes them out for a drink, hangs on their every word and treats them like the most fascinating creature that ever walked the earth, they fall hook, line and sinker. It is the talk that really matters. The sex usually comes later.
Talk, as far as women are concerned, is not cheap. Intimacy is about communication, whether it is verbal or physical and, if the letters I get from women are anything to go by, once verbal communication goes out of the window, sex goes out of the bedroom.
Women need to know they have a unique emotional connection with their partner: that is why they can't bear to have it shattered by another woman.
A friend of mine who is in the feverish honeymoon period of a new love affair, goes into freefall if a day goes by when she doesn't get a text from her boyfriend - no matter how great the sex they have is when they are together.
'I don't ask for much,' she complains. And she is right. It doesn't take much to keep us happy. Which is why some women are prepared to forgive a sexual betrayal - if only their husband still loves them and is willing to work for her forgiveness.
I have even known unusual couples who have an agreement (for whatever reason) that their partner - and that usually means the man - may have sex with other women.
It all works perfectly until their man becomes emotionally involved - because after that it's not actually the exchange of body fluids that matters to us (although we don't much like that, either) it is the exchange of affection.
Perhaps that is why Hillary famously forgave Bill 'I did not have sexual relations with that woman' Clinton - not because she didn't mind a spot of out-of-hours canoodling, but because it was obvious that her husband had no feelings for Monica Lewinsky other than lust.
'That woman' was never any threat to Hillary because she may just as well have been a blow-up sex doll. But what of the reasons for these differences between the sexes?
Why can women forgive sex whereas men can't? The thing is, like it or not, as far as evolution is concerned, we really are built differently.
Men are made to spread their seed as far and wide as possible to ensure the continuation of their genes, while female survival means securing a mate to protect her children.
When there are a few hundred predators stalking the landscape outside the cave, you had better be sure you have got a hunter-gatherer by your side.
What he does when he is out on one of his late night forays is his business, as long as he brings home the bacon. But when he stays out scattering nuts and berries outside another woman's cave, your very existence, as well as that of your children, is in serious danger.
For women, love is not simply a question of champagne and flowers. It serves as a bonding process to keep men by their side, so for them it's an urgent matter of survival.
There is a science to all this, too. Dr David Goldmeier, lead clinician at the Sexual Function Clinic at St Mary's hospital in London, says: 'It's easier for men. We have 15 times the levels of testosterone, so if we see the right female, we're off.'
Whereas women have, what he calls, 'responsive desire'.
In other words, women need to feel an emotional connection to the man in their life - and if they feel that connection has been broken because of another woman, they can struggle to ever forgive their man.
So when Yvonne Keating (or any other woman) says she is more devastated about her husband's emotional than sexual infidelity, she's got science - and evolution - on her side.
By Sally Brampton
Source: Mail Online