It's a little funny you brought this up. I personally don't care much for cheating, but my best friend recently had his marriage fall apart because of such behavior.
You see, he entered into an "open marriage" (wherein both partners have the ability to sleep with other people under the pretense they are only doing so for the physical act, not with the intention of falling in love with someone else, whatever the hell sense that makes) and had been married for about five years. He recently ran into a woman whose marriage was falling apart, and he swooped in figuring she'd just want a rebound sex partner. Thing is, my friend somehow or another felt himself falling in love with her, and announced this stupidly to his wife. Naturally, she got very upset, and this sparked a large debate between them that has now come down to divorce (she took off on him last Thursday while he was at work. she grabbed a few personal items and left him a note and took off 800 miles away back to her home state). Thing is, it is really hard to figure out if he was thinking correctly because he has admitted to not really caring about this new girlfriend, as they have broken up at least twice in the past six months they have been "officially" a couple. As a matter of fact, I believe they just broke up again about two days ago, probably over the fact that now he needs a new place to live since he can't float the bills in the townhouse he was sharing with his soon-to-be ex-wife by himself.
I will openly agree with anyone that what he did was stupid and selfish, and he rightfully is getting what he deserves because of his own lack of good judgement and sense. However, he's running around on Facebook, posting pictures of the note his wife left him about leaving him, and complaining about this is so unfair to him. Unfair to him?! He openly cheated on his wife, she got rightfully pissed and left him, and now he's upset that he's going to have to deal with the consequences of his own actions. People like that really chap my ass because they create a situation like that, and then get mad when it blows up in their face.
So yeah, I don't cheat. If you are lucky enough to find someone who can care about you and accept you for all your faults and shortcomings and still look forward to spending time with you, don't be a dumbass and screw that up for some outside nookie. Sure, there are plenty of fish in the sea, but once you've already hooked a decent one, why would you keep fishing? Because you can? Or perhaps you believe you are some deity's answer to the opposite sex? If you truly believe you are that irresistible, then you have no business in entering an exclusive relationship with one and should be upfront about this with anyone who takes a serious interest in you, and you have no business leading people on into thinking they will ever have a meaningful and serious relationship with you. "Hate the player, not the game" my left nut... if you admit to playing a "game" with people like that, then I sincerely hope you are among the first to catch the Super-AIDS. Or maybe at least herpes... anyone thinks I'm wrong, I'm open to serious discussions about your own admitted stupidity.