Take a look at the introduction of substitution

Body double is an American comedy film released on May 7, 2004, directed by Wallace Wolodarsky and starring Jay Mohr. Substitution tells the story of a young couple, Ed and Alice, who are only one month away from their wedding. Alice happened to see a friend sleeping with a stranger at a party. Alice feels that her sexual experience is not very rich. She suggested to Ed that they should exchange sexual partners with others until they got married. Although Ed strongly disagreed, Alice insisted. Of course, things are not going well, and the relationship between Ed and Alice is being tested.