Unfaithful (IMDB) (Netflix)
From 1934 until the late '60s, Hollywood films were subject to The Production Code, which --among its many specific rules--required that any character's bad deeds were punished. "Unfaithful" could not have been made under that system, but is a better movie for escaping those constraints.

Diane Lane is the wife who strays, and with this role, Richard Gere has ridden his career arc from American Gigolo to cuckold. Olivier Martinez is the young seducer, and succeeds in titillating all the women in audience while making the guys just want to smack his skinny little French--well, you get the picture. The performances are strong (director Adrian Lyne, who did 9-1/2 Weeks, Fatal Attraction and Flashdance, demanded an exhausting number of takes from the actors) and the technique of pumping smoke into the set provides an arty feel. The kid who plays Dewey (my favorite character) on "Malcolm in the Middle" does a good job as the couple's son. What takes this film up a notch is that there's no convenient justification made for anybody's actions: the affair, what happens when it all goes pear-shaped, and the aftermath. In one respect, no one gets off easy, but strict moralists will be frustrated.