Well, why shouldn't they? Because it's wrong. But is it? Cheating is in many ways in the eye of the beholder, for most of what passes as cheating is not seen as such by the cheater, as Shermer (2004) argues. Most of us believe (and this is not simply a matter of self deception) that we are in fact doing the right thing most of the time. This paper examines the psychology behind cheating, looking especially at those instances in which the person whom others believe to be or accuse of cheating see themselves in a very different light.
The question of why people cheat depends in large measure on what arena of human action we are talking about. If we are talking about sex - and "cheating" is probably applied to sexual behavior and infidelity more than to any other arena - it has a great deal to do with human fragility. And especially male psychological fragility. And the rate at which men cheat on their partners (first estimated in the Kinsey report and verified since) suggest that there are indeed a large number of fragile men out there:
To whatever degree, men do cheat and they do it more than women. In the original Kinsey Report, published more than 50 years ago, approximately 60 per cent of men, compared to 30 per cent of women, were unfaithful to their spouses before the age of 40. Those numbers have remained much the same in subsequent studies (http://www.ivillage.co.uk/relationships/couple/cheat/articles/0,,149_158061,00.html).
When men - or women - are unfaithful to their partners because they are seeking a kind of security and/or emotional reward that they cannot get with their regular partner, then they are doing what comes naturally to all types of cheaters in a range of situations. They are trying to change the rules of the game because they have determined that there is no way in which, playing by those rules, that they can win.
And here you are probably saying to yourself - "Wait a minute - that's
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