The Philosopher 1989 one on netflix

The obscure philosopher Georg Hermes almost withdrew from the world to concentrate on his studies, especially Heraclitus, having no relationship since his mother’s death. When he wants a new suit for a lecture (actually very minor) about his new book, he meets the sisters Franziska, Breate and Marthe, who run a boutique, share a house and have a lover each. Those invite Georg to dinner, Franziska even on dates. Falling off a boat he gets naked with her, and they become lovers. The girls all take to Hermes and get him to move in, spoiled by all and offered polygamy.