A Tale of Springtime (1990) on Netflix

Simple conversations engender complicated human interactions. Jeanne is open and even-tempered, a philosophy teacher at a lycée. Her fiancé is away and she doesn't want to stay at his messy flat; she's loaned hers to a cousin, so she accepts the invitation of Natasha, a music student whom she meets at a party, to sleep in her father Igor's bedroom because he's always with his young girlfriend, Eve. Natasha tells Jeanne a story of a missing necklace and her suspicions of Eve. They all meet at dinner, then again at Igor's country house. Is Natasha scheming to get Igor and Jeanne together alone? Once alone, what determines how they choose to act? And the necklace, what of it?