The 3 Phases Of Eve (1972)

Eve has a problem: she believes she has three separate personalities, one of which is prudish, the second of which is sexy and seductive, and the third is an all-out, wild-eyed nymphomaniac. She relates to her doctor all of the sexual adventures each of her personalities engages in. One day she finds herself in the middle of a swingers orgy and calls her doctor for help, which he is more than happy to give her.