The House of the Bories (1970)

A family,the father,a grumpy scientist,his beautiful wife, and their two children live in "La Maison Des Bories, a remote house in a hot sunny part of the Provence. There comes a young man Karl Stephan, hired as a private tutor, who falls in love with the mother (who falls for the teacher too).. They will become platonic lovers. Isabelle Durras is a modern princess of Clèves who favors duty -or her family here- over sex.