Why do a lot of men bother getting into relationships with women and even get married?

Only to find themselves shocked or in utter disbelief when women express disdain or have a problem their men watching porn, going to strip clubs or checking out (or flirting with) other girls etc? Why justify such behavior with the "boys will be boys" excuse, only to get emotionally involved with a woman. Why not just visit sex workers and just get physically involved with women? Just "be a guy" and make love with women, don't fall in love with them.