I thought I did, but I will be more explicit. When marrying her, he is making an implied promise to be monogamous, at least in western culture, where there is an expectation of monogamy. That is why you can sue for divorce in some states on the grounds of a spouse being unfaithful. If he plans to NOT be monogamous, then he simply needs to let her know that before they marry.
And I don't see how that is the same a women being friends with men. Unless by "friends", you really mean "lovers".