Cheating American Style (1988)

This is the story of a man who's finds out, on his wedding day, that his wife cheated on him. In his sadness, he wanders the streets. A bum befriends him and tries to console him, by explaining that cheating happens to everyone. And gives examples of other cheating wives. Such as a woman who cheats on her fiancé with the best man in an elevator, to a housewife who seduces a bible salesman. What he learns is that cheating is the American way.