Vito said, "Do you spend time with your family? Good, because a man who doesn't spend time with his family can never be a real man." I took that to mean that he accepted the standard Mafia "morality" that it was ok to play around as long as you didn't abandon your family (meaning take care of the wife financially and see the kids).

After Sonny's gaffe, he said, "Whatsa matter with you? I think your brain is going soft because of the comedy you play with that young girl." I took that to mean that a) he was sticking it to Sonny because he shot off his mouth; and b) carrying on openly with Lucy at the wedding was a disgrazia.

Interesting that there's no hint that either Vito or Michael ever played around. Probably more interested in power than sex.