Born to Be Bad (1950)
Christabel fools everyone with her sweet exterior including her cousin Donna and Donna's wealthy fiancée Curtis. The only one who sees through her facade is Nick, a rugged writer who loves her anyway. Christabel also loves Nick, but she loves Curtis' money more. After convincing Curtis that Donna is only interested in him for his money, she tricks Curtis into marrying her. Of course, she still dallies with Nick on the side.