Excess Alain Delon completism. Prompted by Glenn Kenny's review in 2021 — a Critic's Pick! It took me several goes to make it past the first half hour.
The scenario has Delon holidaying with hot stuff Romy Schneider at a friends' villa in the south of France. She's a writer of some kind, as was he before he failed into advertising. They're still heavily into each other despite it being about two years since they met and both being powerfully inert apart from the scenes of staged friskiness. A friend/erstwhile lover in the tunes business arrives with his previously undiscovered nubile daughter causing the usual complications. Things then grind on as they must.
It's sexy in a camera-objectifying-female-bodies way; the male gaze is all we get as the women are too busy looking at the men. I found it boring as not much effort is put into developing the characters; for instance it's clear that Delon isn't drinking but we are never given a reason why. Another scene has Schneider getting annoyed at her chopsticks. The attempt to turn it into a detective flick in the last movement is lighter than air.
It's tagged at IMDB as a psychological drama and I guess you could bracket it with minor Hitchcock like Spellbound. At times I wondered if it was taking on more of Who's Afraid of Virginia Woolf? than it could swallow.