Loving Friends (1979)

Have you ever wondered about the psycho-sociological consequences of urban flight? Neither have I. Nevertheless, it receives the hardcore treatment in Loving Friends where Sharon Kane and her two girlfriends demonstrate that polymorphous perversity is alive and well in the suburbs. When they're done fucking the delivery boy, they fuck each other. When they're done fucking each other, they fuck each other's boyfriend. When one of them cries "Enough!" and threatens to move out, the other two plan a surprise party where she will have "more guys than she can handle" and, in the grand finale, prove the old philosophical point that there's no such thing as "enough."