It Was Infidelity in the Beginning (1999)

Original title: Am Anfang war der Seitensprung

Annabelle is annoyed by family life. Most of all, she bothers her health-conscious, chain-smoking, know-it-all mother, Edda who visits regularly. When mother moves in her house for three months, because their house is being renovated, She enthusiastically takes the chance to go on a "relaxing weekend". On this occasion her girlfriend Doro, who was supposed to take care of the children, starts an affair with her husband, Friedrich. When she returns, she is appalled. She packs her things and leaves Friedrich and the family. Promptly she meets a young student at a party, who awakens the passion in her. Written by lament