@rebelen13 - I don't know why people do it either. I have never cheated and never would. I've seen the damage it does the other person, let alone if there's kids, etc involved. Could be self esteem. Maybe just bored in the mindset that the "grass is always greener oh HER side".

I also agree with byrd and aronado on legalizing it in extreme cases such as child molestation & rape.

Real options? Truthfully, I don't think there really are any. This is where it gets sticky for many people because, IMO, straying/adultery is usually seen from a religious point of view, i.e. bible, marriage vows, etc. Many people aren't like that, though.

In my perfect world: Maybe if there was 100% proof,  no room for doubt, then maybe something could be done to him/her. Proof like: photos, video, audio, emails... or whatever. At the very least people like that should be maybe sterilized. People like that should not breed. Alot of people see punishment as being financially punished. Fines? But that seems kinda retarded to me, but hey, whatever works, right?

Sorry for long-winded reply here. But really, it's almost impossible to "get back" or "hurt" people like that that stray simply because they don't really care about your relationship to begin with and obviously don't possess much of a conscience. Again, this is only my opinion here.