I guess there could be many reasons, really, but it is a mistake to think that its all about sex. Ok, sex is important and a woman wouldn't cheat on her husband with someone who is terrible in bed. Having said that, there surely has to be more to it.
Feeling wanted and appreciated. Playing out sexual fantasies. The trill of the unknown... these are just some of the reasons why married women look for affairs.
Also consider the fact that after many years of living together and rising children, some people just don't look at each other in the say way as before. There is a particular role you need to play in the house, which doesn't really include you being sexy.
