Kung-Fu Master!
On a rainy day in spring, Mary-Jane, a woman of almost 40, falls in love, or rather slides in love with a boy of nearly 15, Julien, a classmate of her daughter.
Starring Jane Birkin, Mathieu Demy, Charlotte Gainsbourg, Lou Doillon, Gary Chekchak, Frank Laurent, Eva Simonet, Judy Campbell
Watch "Kung-Fu Master!" from streaming services Criterion Channel, Fandor, Fandor (Prime) released in 1988. It's a drama and romance movie, and has a rating of 6.9 out of 10 from Imdb which is usually fine for this kind of movie.