DAS MIKROSKOP ("The Microscope") is the first part of Rudolf Thome's "Trilogy of Love", which was completed with "The Philosopher" (1988) and "Seven Women" (1989).
The film is about a couple who love each other, but whose relationship is on a dead end. The man embarks on an affair with an acquaintance, in the hope that it will bring new energy into his life. But his previous partner is not ready to give up the relationship so easily. She befriends the new woman and finally shows her partner that old things can indeed seem new.