Adultery is far less common in intact marriages. Most marital partners are faithful most of the time. In fact, the surveys also show that the large majority of those questioned believe strongly in marital fidelity, certainly for their spouse and generally for themselves. Even if monogamy is not always achieved, it remains the ideal.

It has also been found, in rare cases, an affair may help solve a problem by forcing it into the open, but in fact, it’s no more likely to help a marriage then some other major crisis, such as the house burning down or the baby dying. A fine watch may be repaired by kicking it, but that seems risky.

The truth is, most affairs do great damage. Ove all, 53 of the 100 adulterous marriages Dr Chauhan surveyed, ended in divorce. This in spite of the couple’s decision to seek counselling and my own best efforts to help them. By contrast, it is unusual in his practice for non-adulterous marriages to dissolve.

Since an affair involves sex, it is often assumed that the affair is about sex and the lover is either very attractive or some kind of sexual athlete. In Dr Chauhan’s experience lovers are not necessarily about sex. Thirty of the people he surveyed for instance half men and half women acknowledged that their sex lives at home were perfectly adequate. It was not sex but the lack of intimacy that had compelled them to have an affair.

Many of those he talked to told him their decision to cheat on their partners was largely motivated by anger. Twenty five in his survey were angry about some aspect of their spouse’s behaviour or were retaliating for affairs their spouses had initiated. Interestingly, even those who seek out such relationships may become uneasy at the motivating emotions. The reasons for affairs are complex and varied. Most of them have to do with problems the person having the affair is experiencing rather than the desirability of the ‘other’ man or woman.

People involved in affairs like to convince themselves they are doing their loved ones a favour by hiding the unpleasant truth. But according to many psychiatrists this is unrealistic. Spouses usually known when they are being lied to they just don’t know what the truth is, and if it is bad enough to lie about, they suspect the worst.

Honesty is the central factor in intimacy. Even the smallest lie can have terrible implications. In the cases I’ve seen, lying about an affair only made things worse. Many marriages end in the wake of an affair, but many more end in an effort to maintain the secret of the affair.

Certainly, an affair can trigger a crisis in marriage. After any crisis, a marriage may with a lot of work and pain recover, or it may become worse. There are people who would find it impossible to live in a blemished marriage, and there are marriages in which the unfaithful spouse remains on probation or under punishment for decades after the affair.

As in every other aspect of marriage, it all comes down to communication. "If there is one conclusion I can draw, it’s that monogamy works," says Dr Narendra Chauhan. It isn’t rare it’s practised by most people most of the time, and always has been. It isn’t difficult anyone can do it, and only the smallest sacrifices are involved. Monogamy isn’t even dull living without lies and secrets opens you up to being known and understood, and certainly that isn’t dull.

If people would only trust each other enough to work towards honesty and intimacy within their marriage, then may be they could do what everybody wants to do and most unfaithful spouses are afraid to try, live together happily ever after.