Honestly, anything by Eric Rohmer (apart from My Night at Maude's and La Collectionneuse, they really didn't hit for me, although they're often cited as his best, but whatever, those people are wrong w/e), but I think this one is a great place to start. It's such a weird little story. A 20-year-old guy is dating a 25-year-old woman who, before him, was having an affair with a pilot. One day he sees the pilot leave her apartment building, and becomes obsessed with the idea that she's cheating on him. High jinks ensue and what starts as a fraught emotional drama gives way to a Hitchockian thriller, when he teams up with the cute, sparky blonde high schooler he meets in a park to investigate.
Ultimately, it's a film that's all about the labryinths we create because of jealousy, and the choices we make, either to sit on the outside of our life looking in or to get inside and star in the story - and actually believing that we have that choice in the first place. Anyway, I love it! Vive la France! 🇫🇷