Strangers (1972)

Paul is married to Andrea and they love each other very much but have become bored in the bedroom. They’ve tried all sorts of role-play fantasies and kinky sex, but decide to buy a swinger’s magazine out of curiosity. They decide to meet up with Tom and Marie, who owns a 32-foot yacht. They have a good swap session but want to keep looking. They finally end up at the Venus Swing Club but are surprised by what they see.