In This Our Life (1942)

In this melodrama, pampered sibling Stanley Timberlake (Bette Davis) is 24 hours away from marrying her lawyer fiancé, Craig Fleming (George Brent), when she absconds with Dr. Peter Kingsmill (Dennis Morgan), the husband of her sister Roy Timberlake (Olivia de Havilland). To clear the way for her sister's marriage to Peter, Roy quickly divorces him, but then starts seeing her sister's former fiancé, Craig. Stanley's true nature begins to reveal itself, forcing Peter to look for a way out.