Rowan Pelling: Unfaithful? He didn't mention it

In my office there was just one comment on the reported dalliance between David Beckham and his PA that made every woman wince. It was the source from Victoria's camp who said of the artiste formerly known as Posh (before a more upmarket bird roosted on the scene), "The tone of the text messages are just not David. They never send sexy texts to each other, so she can't imagine him doing it with someone he barely knows." Nurse! We need morphine here - that's just too painful. How could such a worldly young woman show such agonising naivety in what was clearly supposed to be a PR counter-offensive? It was as if she had said, "He can't have gone skinny-dipping in Goa, because he's never done that in Grimsby."

The allure of affairs resides in the fact that they promise holidays for the libido where you temporarily experience the sort of sexual climate that is meteorologically improbable in long years of domestic routine. The entire point of playing away is that you don't do whatever it is that you do do with your spouse. Both genders are guilty of such behaviour, but men tend to carry the practice to embarrassing extremes. It's male MPs who suddenly start writing teenage-style, mawkish odes to their researchers, when they can barely grunt at their partner over the cornflakes; men who buy Janet Reger silk panties for their secretaries when they can't remember their own wedding anniversary. The only scene that resonated with true emotion in the otherwise saccharine mess that was Love Actually was when Emma Thompson's betrayed wife realised that the fabulous necklace she had chanced upon before Christmas was always intended for someone else.

Women resent romantic discrimination far more than the actual act of infidelity. Nothing is more insulting than seeing your husband treat another woman as a total sex goddess, who must be worshipped with trinkets and panting text-sex - especially when you got a Magimix for Christmas and the last time he talked dirty to you was when the septic tank needed emptying.

The thing that Victoria Beckham, for all her appearance of feral cunning, has failed to grasp is that people are basically unfathomable. Just because he doesn't do or say it to you doesn't mean he'll never do or say it to anyone else. The better you know someone, the further their hidden depths recede from your consciousness as you forge new emotional territory together, like snow gently covering an iced-over ravine. A wise person will always keep in mind their partner's essential otherness, the mystery of their private thoughts and impulses, and the fact that over the years even the most entrenched couples tend to grow, in John Bayley's memorable phrase (describing his relationship with Iris Murdoch), "closer and closer apart".

I have often thought that a writer's ability to wrong-foot the reader with sudden, utterly uncharacteristic actions in the people they create is one key way of distinguishing a great novelist from a good one. The late Angus Wilson, author of Anglo-Saxon Attitudes, was a genius at hauling up his monsters just the right side of caricature by unexpected displays of some hitherto latent humanity. But nowhere are people more unpredictable than in matters of the heart.

Just a month ago a self-made businessman and father of two, Peter Lee, an adviser to the Government on disabled transport policy, was jailed after wrecking his bus company by stealing more than £500,000 over three years to lavish on a London prostitute. Lee's business partner said bitterly, "[He] has cheated on his family, his employees, his business and his colleagues." Behaviour that by all accounts was totally "out of character".

If a stolid and dependable accountant can lose all sense of decorum in the presence of a luscious bit of skirt, it's hardly surprising that a footballing demigod left largely to his own devices in Europe's party-central city should be diverted by a spot of dirty text talk. The truly amazing thing is that his wife should think him incapable of it.