The Surrogate (1984)

Frank and Lee have marital problems: he's been impotent for 18 months, she alternates between sympathy and criticism. His temper gets the best of him, so he's seeing a psychotherapist who finds the anger and the impotence related. She recommends that Frank and Lee hire a mysterious European woman to lead them through fantasies intended to unlock passion and help them heal. At the same time this is going on, the police are investigating a series of stabbings: as corpses pile up, we wonder if Frank's temper may be behind this; or perhaps it's Eric, a cross-dressing neighbor and friend of Lee's; it may even be the European woman, who keeps popping up with new fantasies.