Le Bonheur (1965)

Jean-Claude Drouot is a young carpenter with a happy marriage, two bouncy bairns, and a broad on the side in Le Bonheur (1965), the first color film by French director Agnès Varda. Despite the odds, Jean-Claude is no dim clod—he's not trying to ruin his marriage or hurt his wife so much as enrich their bond and improve his life, and somehow cheating on Claire Drouot seems like the way to go. He's madly in love with her, but he just happens to be madly in love with Marie-France Boyer too, and his love for one strengthens his love for the other (no doubt helped by the fact that both get le nude). But what will happen when he tells his missus that he has a mistress? Hint: Things turn bad once the cat's out of Le Bag.