I agree that if the person wants to they will, but a good way to prevent someone who typically wouldn't from doing something like that is to treat them right! Don't leave anything lacking in the relationship and that doesn't just mean sex! Include them, spend time with them, share interests, occasionally try something that's new to both of you! Make sure they feel loved and appreciated. Have open communication.

Those are the best ways to prevent cheating in a person who would be on the fence about things like that, or typically wouldn't.

To those who just are that type of person if they've cheated in the past and it wasn't due to their partner not doing what I've stated above chances are it will happen again and if you are ever the person they cheated WITH, don't think that because they cheated with you that you're special, because often, there is someone special on the side if they are with you too.

Honestly, I can't stand cheaters!

I have always said that you can't make a person not cheat. And you can't spend your time worrying if they will. Like Peggi said, focus on the relationship at hand and keeping it healthy. Also, you have to put effort in making yourself happy and content as well. Nothing is sexier to me than a person who is confident in their own skin and knows what makes themselves happy. If you are putting your focus on the health of the relationship, your partner and yourself and they still cheat, they aren't worth your effort and you should move on.

It's true. You can't stop someone from cheating. I used to think that if I kept a man sexually satisfied that they would not cheat- we had loads and loads of sex! Even when I was not in the mood I never said no. He cheated anyway. I can't stand cheaters either!

If they are going to cheat they will do it no matter what you do to please them

OK, I won't disagree with the previous posters here. However, I will say that even though you cannot prevent a cheater from cheating, you CAN push a NON-cheater into someone else's arms. Communication is key, in my opinion.

Short of chaining someone up and keeping them against their own will you can't completely fool proof prevent a human from doing ANYTHING.

Are there things that will likely drive someone to cheat? Sure. Are there things that will reduce the chances, absolutely. But there is no formula.

I'm pretty much going to echo most of the things said already.

You can't control someone...and it's not a good thing if you could.

If a person doesn't have a reason to cheat, they won't. Some people just aren't capable of a monogamous relationship either. It'd be best to avoid such a thing with them anyway and just leave them if they stray.