The Sex Monster

Marty Barnes gets more than he wishes for when he asks his wife to join him in a menage-a-trois. She loves it and he has created a Sex Monster.
A neurotic L.A. building contractor (Mike Binder in his best Woody Allen imitation) pushes his wife (Mariel Hemingway) into entering into a three way sexual relationship. Unfortunately for him, his wife gets more out of it than he does and becomes a tigress seducing every female she meets including the contractor's secretary.