Despite how old-fashioned it seems now, Payment on Demand probably represented a pretty progressive attitude toward divorce in 1951, just in broaching the subject in a straightforward, non-sensationalistic manner. It seems horribly retrograde now, of course, with its harsh judgment of a woman's desire for even a modicum of independence and self-determination, but you can see the wheels of progress turning slowly but surely in the background, in the ways that some characters interact and respond to the news that wealthy businessman David Ramsey (Barry Sullivan) has decided to divorce his wife of many years, Joyce (Bette Davis). Yes, there's the sleazy married guy who hits on Joyce as soon as he learns she's divorced, and yes, there are the patronizing lawyers and private detectives who take advantage of her distress. But there's also a surprisingly sympathetic and nuanced reaction from Joyce's society friends, as well as from her young-adult daughters. You get the impression that by the time the younger Ramseys get around to potential divorces, things will be a whole lot easier for them.
Director and co-writer Curtis Bernhardt sort of stacks the deck against Joyce, though, showing her as a manipulative social climber who pushed her husband to become a high-powered rich executive when he would have preferred a simple rural life. It's an interesting performance from Davis, because Joyce isn't just a conniving villain that Davis can play with maniacal glee; she's a flawed woman who's a bit insensitive and calculating in her efforts to achieve what she believes is best for her and her family. Bernhardt sets up periodic flashbacks throughout the movie, showing the development of Joyce and David's relationship from early bliss to eventual resentment (it's sort of like the 1951 version of Blue Valentine), and Joyce is clearly the bad guy in many of them, but she doesn't do what she does out of malice. Davis plays her more as sad and misguided, and it's a shame that the movie essentially dismisses Joyce's interests and goals, because they are entirely legitimate.
Regardless of Joyce's shortcomings or genuine concerns, of course the movie has to head toward her and David patching things up, although at least it resists tying things up as neatly as, say, a movie made 10 years earlier might have. Bernhardt allows for ambiguity in the flashbacks (which use an interesting theater-style technique of constructing walls out of translucent material that gives everything a sort of artificial feel), and he even gives David's mistress probably the most progressive attitude in the whole film. When she and David are discovered by the P.I. Joyce has hired, he desperately offers to marry her so that she won't have to endure a toxic scandal. But she brushes the idea aside, asserting that her friends and associates won't care that she had an affair with a married (but separated) man. Throughout the scene, lush classical music plays like the swelling score of an old movie, and when the mistress tells David she's through with him, she shuts off the record player in her apartment and abruptly cuts the music. It's a stark and creative way to show the contrast between generational attitudes, and an indication of the sophistication that this movie has in spurts, even if it's a little dull and conservative on the whole.