My DH has never cheated and I don't believe he ever would, having been on the receiving end of that himself in the past. I have a lot of male friends- one has an open arrangement with his DW, another is in a polyamourous relationship. I only know one that I know to have cheated on his wife- they are now seperated.
I'm sorry your Dh cheated on you it's a terrible breach of your trust. But you can't tar all men with the same brush.
Having s3x when you don't want to won't save a marriage IMO- if someone wants to cheat it's not because you don't give them enough s3x, it's because they want s3x with someone else. It's not your fault- it's theirs. JMO.