Sometimes, it's easier to stay in something even when you're not happy, than it is to be brave and take the plunge and end it. Rather than go throught the motions of a break up, some people would rather have an affair. I think that way you end up getting whatever it is you're missing at home whenther it's attention, romance, sex etc etc, without having to deal with your porblems the right way.

In short, it's the cowards way 'out' IMO.