welll.......I personally have never cheated; flirted shamelessly in my younger days, yes...but never came close to cheating.
That said...
I tend to be more AWARE of other men when me and mine aren't getting along. For example, say he never opens doors, shows public affection and this is on my mind, I WILL notice a man who does these things and think "why couldn't he...."
Women tend to be more retaliative also, so if they suspect that their man is cheating or even thinking about someone else it may give them the desire to "get even" and many times they may use their sexuality to do this.

If their man isn't paying attention to them is another reason. The idea seems to be that men who cheat would cheat regardless of if they have a dimepiece who cooks for them every day and fulfills their sexual appetite...the "ego" theory, or just lack of physical control, while women who are satisfied with their partner are less likely to cheat. The idea that men cheat more frequently than women goes along with the idea that women are able to reach a level of complete satisfaction while men are "unsatiable"; doomed to "settle" and the ability to remain faithful counts solely on their ability to ignore their need for something "more" than what they have. I don't know if this is true, but I've never had a desire to "jump someone" while I was with my man, at least not enough to actually do it, even with ample opportunity. Not to say that I haven't met men that I know I would be interested in pursueing if I were single, I just knew I was not callous enough to deal with the guilt afterward.

my overriding opinion? There are just some cheatin ass people in general. I've known women who do it, indiscriminately, and don't see anything wrong with it. I've also seen men who contact their female friends stating that they are involved with someone and would not feel comfortable getting together solo with them anymore, even if it's innocent.