"Alimony" from 1949 is a low budget film that nevertheless sports a good cast: John Beal, Hillary Brooke, Martha Vickers, and Leonid Kinsky.
Beal is a composer, Dan, who narrates his story in flashback when he is visited by Kitty (Vickers) father, who is trying to find her. Dan admits that he hasn't seen Kitty in a couple of years.
Dan lives in a convivial rooming house along with his fiancee Linda (Brooke) though they don't share a room. It's 1949 after all. Dan stays up until all hours of the night playing his piano, but no one ever complains.
Kitty comes along, and, once she hears Dan's compositions are going to be used in a new Broadway musical, decides that he's all hers. And Dan falls for her. He breaks up with a heartbroken Linda.
The musical falls through, and Kitty is out the door. Dan is left to try to win Linda back. No problem. She succumbs in no time. Dan, however, in the throes of amore, has written a song for Kitty. It becomes a big hit, and now the two are inextricably linked, even touring together, to Linda's disgust. But she decides to fight for her man and get him back. Again.
Not much point to this. I met John Beal some years ago. He was a lovely man and better than this!