Only some men
Some men have more sex
drive than others and perpetpetually need to prove their virility with ouside "conquests", some man are even sex-a-holics and are perpetually on the prowl.
Some wives put up with it, some don't and leave & some ignore what's going on. Cheating men tend to stay with their wives either for the sake of the kids or because their wives may well be the best women they know.