I don't cheat on my wife because I wouldn't want her cheating on me.
I think diseases are also a deterence.
That said I would admit the first thing I judge when I see a woman is whether I would like to have sex with her. There is a saying, "It's not where you get your appetite, It's where you go for dinner."
I guess the biggest thing is not to get yourself in situations where you could get weak and succumb to your desires.