Simple Passion (2020) on Netflix

Plot summary

Hélène is a literature professor and divorced mother. She lives in the Paris suburbs with Paul, her preteen son. At a party in Porto she meets Alexandre, a Russian diplomat who is younger than she is and married, stationed at the Russian Embassy in Paris. They begin an affair and meet in the afternoons at her house. Alexandre is cold and evasive. He visits only when it suits him and tells Hélène never to contact him, especially when he is away with his wife. Hélène waits for him to call, and her obsession with him grows.