A Girl, a Guy, and a Gob (1941)

Steve is a shy quiet man who is an executive for a shipping firm. He meets Dot at the Opera where she had his seats and the next day she shows up as his temporary secretary. Then Coffee Cup comes to town to see Dot, his gal. When Steven is with Cecilia, everything is boring. When he is with Dot and Coffee Cup, everything is exciting and he falls for Dot. But Coffee is getting out of the Navy in a few days and he plans to marry Dot.