BlackJack (1990)

Kaj, Lennart and Robert are 30-somethings who goes out to dance every weekend. At one dance they meet Inger, whom Kaj falls in love with. Kaj has some friends who are playing in a band. The drummer Tommy is known for being the local Casanova, seducing women when ever he gets the chance. It doesn't take him long to have an affair with Inger, behind Kaj's back.