As many people have pointed out, there can be exceptions, but in general, this is probably a reasonable truism. As a man, feeling the way I do, I would say that a cheater will cheat again if the underlying problems that lead to the cheating in the first place are not addressed.
Most people believe that the cheater takes all the blame. Few think about what caused the cheater to cheat, and even if they do think about it, they don’t think it matters. It’s a matter of black and white, for most. Cheating is wrong.
Still, I think that if you don’t think about what lead to the cheating, you can’t stop the cheater from cheating. They are looking for something important that they are not getting in the relationship. Since they aren’t getting it, and it is extremely important to them, they go outside the relationship.
I would say that if you find out what this is, and find a way to address it adequately, the cheater won’t cheat again. If you don’t acknowledge it exists (no one who is cheated on feels like they have to take any responsibility for what the cheater did), then you can’t fix it. The cheater will cheat again.
I suggest this as a matter of practicality, not moral appropriateness. If the relationship is valuable, then the moral outrage that is felt by the cuckold must be set aside, because it will get in the way of addressing the problems in the relationship. If you don’t address the problems, you can’t stop the immoral behavior.