Glück im Hinterhaus (1980)

Karl Erp is a fairly well-off librarian in his mid-forties with two children and a boring marriage. His love for his intern, Miss Broder, brings him out of his lethargy. He tells his wife, Elisabeth, that love never existed between them and that he only married her as a favor to her. He then moves in with Miss Broder. Harassed by her mother, he promises a divorce from his wife and later, a marriage to with her daughter. However, the spark that helped Karl in starting a new relationship doesn't show up in his day-to-day life. He can't find the willpower to start a new life, and he misses his old comforts. Thus, he returns to Elisabeth and their broken marriage.