Les Nuits de la plein lune is Éric Rohmer's fourth episode in his Comédies et Proverbes series, and is set in the new development of Lognes and central Paris. The 'proverb' 'Qui a deux femmes perd son âme, qui a deux maisons perd sa raison' ('The person who has two women loses his soul, the person who has two houses loses his reason') was is fact invented by Rohmer himself.
This being a Rohmer film, it's about love, although of course seen from a different angle. In a nutshell, the designer (of lamps, as in moonlight) Louise (Pascale Ogier) is living in the Parisian suburbs with the possessive and older Rémi (Tchéky Karyo), who isn't interested in partying as Louise is. He's annoyed when she returns for some of the week to her flat in central Paris because she wants some space, to be on her own. She tells him that she loves him deeply and that their relationship will in fact benefit from the new arrangement. In reality though she spends a lot of time with Octave (Fabrice Luchini) with whom she has a platonic relationship. But at a party she meets Bastien (Christian Vadim), to whom she's sexually attracted and with whom she sleeps on one occasion, slipping from his flat in the early hours to return to Rémi. But Rémi isn't there, he's on his way back from a friend of a friend of Louise's, who's the love of his life. Louise returns to her Paris flat in tears.
Jealousy plays a large part in this film: Rémi's jealousy of men Louise sees, jealousy too perhaps of her youth and vitality; Octave's jealousy of Bastien; Louise's jealousy of Rémi, who she thinks is having an affair with her friend Camille (Virginie Thévenet); etc.
This is a film of the clash of egos, and no one's ego is as monstrous as Octave's. Octave is married but lusts after Louise, who only wants to be his friend. He is a writer, and can interrupt a conversation just because of something he's said that he thinks is of sparkling intellect and that he has to jot down in his note book. He's also a liar, trying to stir things up between Louise and Rémi: when Louise says she's seen Rémi in a café, Octave says he's seen Camille too, planting seeds of doubt in Louise's mind about Rémi's fidelity. And what of Louise herself, who wants to be in a relationship but to be free at the same time: what kind of ego is that? Both Octave and Louise want to have their cake and eat it.
This is the self-deception: Octave, in spite of being told several times that Louise doesn't want the kind of relationship he wants, insists on pawing her, at one stage taking things a little too far and threatening the friendship. Louise is really deceiving herself if she thinks that Rémi is going to fall for her every whim. And for someone who wants to be alone some of the time, the only time she seems to spend in her flat is when she's on the phone trying to go out with someone.
Like an entomologist of the mind, Rohmer examines all aspects of love, its transience, its automatic assumptions, the borders between sexual desire and love itself, the questions, the torment, and so on.