Once a cheater not always a cheater. That phrase is oversused and increasingly untrue.
Some people honestly just do cheat out of desperate need for something they lack, and not maliciously or habitually. There is such thing as making a mistake and not being the type of person to do it to BE a cheater. There is also such thing as making mistakes and learning from them, which a surprising number of cheaters do.
Sure, a LOT of people who are cheaters are emotionally and mentally predisposed to doing so because of their own demons. And yes, they will cheat out of nature or habit regardless.
No one can judge when a "typical" guy will do it again, or if he even will. And typical men dont cheat, typical people do. Women cheat too, dont forget. It is most likely it will be with the same person if he does, or someone similar or in a similar situation. If he picked her up at the gym you can bet he will do it again because that method is tried and true.
But if he is a good man who was remorseful and honestly does not want to stray again, he wont. Neither would a good woman who made a mistake.
Im not judging you or lecturing, Im just saying...If this is your scenario, I would think long and hard about whether you trust him anyway since you are logged in asking this question...Maybe you should leave if you are so convinced its a possibility it will happen again. You can do better.