A Little, a Lot, Passionately(1971)

Didier is an embarrassed lover and husband when his young mistress, whom he had just left, attempts suicide and is adopted by her family while she recovers. The situation becomes very tense when everyone (husband, wife, children and mistress) goes on vacation together. Didier asks his wife for a divorce after succumbing to his mistress again, but that's not the end of the trouble.