Jeanne Moreau gives a remarkable performance as "Catherine," depicting a woman who is quite self-centered and unpredictable, and who uses two men – "Julius/Jules" (Oskar Werner) and "Jim" (Henri Serre) – to her advantage. She’s sometimes married to one, yet feels affection for both of them, or perhaps neither, or even has no connection with herself at all; Truffaut manages these interwoven relationships skillfully. The film's rhythm shifts considerably, moving from fast-paced to slow; the conversations are limited—particularly those of "Jim"—and the movie’s aesthetic changes seamlessly as the story unfolds, beginning before World War I and extending far beyond. The cinematography is often close-up and impactful, and we’re drawn into observing these imperfect people as they age without much dignity while attempting to resolve their situation – who will win her affection; what does she desire; what are her true feelings? As is typical of this director's work, there’s both humor and elegance—and if you have the chance, it’s best experienced on a large screen to appreciate the richness of this production. The film loses some momentum in its final section, and I must admit that I didn't find myself liking any of the characters – but aside from that, it offers an enjoyable perspective on existence when conventional rules don't exist, making it worthwhile viewing.

Source on TMDB