The Tender Trap (1955) on Netflix

Broadway agent Charlie is a man about town with a girl for every occasion. Maybe classical violinist Sylvia tops the list, but she's still just a dame. Best buddy Joe, staying over to take a break from his marriage, watches bemusedly while becoming increasingly attracted to Sylvia himself. When young Julie turns up for audition and rebuffs Charlie's advances it looks like he might be becoming a one gal guy. But she has her own grand plan for her future and if he is to be part of it he will have to make commitments quite awful to contemplate.