Indiscreet - Leo McCarey

On New Year's Eve, Geraldine ('Jerry') Trent decides to break up with her boyfriend Jim Woodward, having finally grown tired of his dishonesty and his infidelities. Soon afterward, Geraldine meets and falls in love with novelist Anthony Blake. Blake knows that she has had a man in her past, but he is content as long as he never finds out who it was. All seems well until her sister Joan returns from a trip, and happily introduces Woodward as the new man in her life.