Back Street

"This film (based on a Fanny Hurst best seller) is way out of date in the modern age. No self-respecting woman would be so willing to sacrifice her career for the prospect of being a millionaire's kept woman. No man, seriously in love with any woman, would put them through such a demeaning situation (they would consider divorce first of all, then remarriage). But there was supposed to be a sense of self-sacrifice by the heroine (Margaret Sullivan) that transcended the entire story."

The point is, this film isn't set in the modern age. There's no sense judging this or any other movie set in another era by today's standards. At the time this story took place, divorce wasn't common. In fact, it was still considered scandalous. Many women put up with unhappy, even abusive marriages, rather than incur the wrath of society that a divorce would have brought upon them. Also, regardless of what her career prospects may have been, a man's career always took precedence. There's no way that he would have sacrificed his family and his career in order to divorce his wife and marry his mistress. There's no way she would have asked him to. This was made very clear in a conversation that took place between them.

When you watch a movie set in another time you need to keep in mind that the rules that governed society are most likely far different than the ones we have today. You need to judge it by those rules or not at all.