Both Mandy Miller and Betta St John decided to quit acting shortly after doing this movie, for no apparent reason other than simply choosing to. Maybe they weren't the most famous actresses in the world, but they were in their prime and had a life long career ahead of them (Mandy in fact hadn't even reached her prime yet).
Strange... how many young actors would do that nowadays?
My theory, in the case of Mandy Miller at least, is that directors in the 1950s were looking for beautiful women to star in their movies. Stars like Marilyn Monroe, Jane Russell, Liz Taylor and many others. Now Mandy was a nice girl and could, kinda, act, but she wasn't really a looker, what with those weird eyebrows. So I reckon she tried to find new roles, but was constantly turned down, then finally she'd had enough and gave up.
As for the other starlet in the movie, I don't know what happened with her. She was really attractive, though.
That's probably true.
I vaguely remember reading somewhere that she said of her acting career: "I was made to believe I was nothing special", or something like that. Not sure if she meant it physically, acting wise or both.