Cousins (1989) on Netflix

The Kozinskis - husband and wife Larry and Tish, and Larry's teen-aged son Mitch - lead a relatively carefree life. Larry chucked in his conventional job in securities to become a dance instructor. Larry's paternal Uncle Phil considers Larry unsuccessful in everything he does... except life. Larry recently married cosmetician Tish, a beautiful, sexually overt woman who is nonetheless insecure since she wants people to think she's smart. Mitch hides behind his video camera, which he uses not only as a crutch but a means to express himself. The Hardys - husband and wife Tom and Maria, and their adolescent daughter Chloe - lead a typical middle class suburban life. Car dealer Tom wants people to think him successful in all aspects of his life, which often manifests itself in cheating on legal secretary Maria, to who family and the sanctity of marriage are the most important things in life. The Kozinskis and the Hardys meet when Phil marries Maria's feisty Italian mother, Edie. At the wedding reception, Tom and Tish are immediately attracted to each other physically, and quickly begin a sexual relationship. Deep down, both Larry and Maria know what Tom and Tish did. In meeting to discuss what to do about their cheating spouses, Larry and Maria form a deep, emotional friendship which blossoms into love. In seeing their respective spouses, Tom and Tish know that Larry and Maria know about their affair, but they also believe that Larry and Maria are now too having an affair based on love, which is not the case. But Larry and Maria, who now seem to be holding the cards, have to decide what best to do for themselves, for their children and for Tom and Tish. Larry's visiting father, Vince, who metaphorically wants to make chicken salad with his chicken, may provide Larry with some inspiration.