Two cousins related by marriage, Marthe (Marie-Christine Barrault) and Ludovic (Victor Lanoux), meet at a family wedding for the first time. Marthe is the bride's daughter and Ludovic is the groom's nephew. After a raucous wedding reception with plenty of dancing and drinking, Marthe and Ludovic are left waiting for their respective spouses, Pascal (Guy Marchand) and Karine (Marie-France Pisier), who are off having sex. While they wait, they get to know each other: Marthe is a secretary and Ludovic is a dance instructor who changes his occupation every three years. Later they dance together, even after the lights are turned off. Eventually Pascal and Karine show up, slightly disheveled, and the couples part.
Ludovic meets Marthe for lunch and tells her that her husband is having an affair with his wife. Later Pascal shamelessly informs her that he's broken off all of his affairs and that from now on she will be the only one. When Marthe tells him she knows about Karine, he says he only had her "three times in the bushes."
Sometime later at a family gathering at Marthe's mother's house, Ludovic's daughter, Nelsa (Catherine Verlor), shows slides she took at the wedding—including compromising photos of Pascal and Karine. During the slide show, Martha's mother's new husband dies. At the funeral, Ludovic's father arrives and extends his condolences; he too lost his spouse recently. On the way back from the cemetery, Marthe and Ludovic get better acquainted, with Marthe revealing that she enjoys swimming and singing.
Later that week, Marthe and Ludovic meet for lunch, buy bathing suits, and going swimming in a public pool. They enjoy each other's company so much that they decide to take the rest of the day off together to go shopping and see a movie. Although their relationship is platonic, Pascal and Karine begin to grow jealous. Marthe and Ludovic playfully arrange to meet by chance at a restaurant with their respective families, to see how Pascal and Karine react. Later that week Marthe and Ludovic meet again at the swimming pool and acknowledge that their relationship is special and must remain that way, even if platonic.
At another family wedding, with Pascal and the groom's father fighting over a business deal gone wrong, Marthe and Ludovic decide to leave and spend the day together. They return to find a drunken Pascal harassing the guests, and soon they all leave the disastrous wedding and bring Pascal home. Marthe's mother and Ludovic's father develop a close friendship and plan to spend time at his vineyard. Marthe and Ludovic discuss their own relationship and decide that it is absurd to keep it platonic. For once they will do something for themselves, and not for their spouses and families.
That Saturday, Marthe and Ludovic meet and spend the day together in a hotel making love. They decide to keep the room for the night and order food in. The following morning they extend their stay another day, making love, exchanging recipes, bathing together, and simply enjoying each other's company.
In the coming days, Pascal reverts to his philandering ways, Karine leaves Ludovic and then returns, and Marthe's mother and Ludovic's father discover they're not as compatible as they thought. Marthe and Ludovic's relationship, however, continues to grow in love. At a Christmas family gathering at Marthe's mother's house, Marthe and Ludovic lock themselves in a bedroom and make love throughout the evening while their families eat, drink, watch Midnight Mass, and exchange gifts. The couple finally emerge from the bedroom, say goodbye to their crazy families, and ride off into the night together.Marie-Christine Barrault as MartheVictor Lanoux as LudovicMarie-France Pisier as KarineGuy Marchand as PascalGinette Garcin as BijuSybil Maas as DianePopeck as SacyPierre Plessis as GobertCatherine Verlor as NelsaHubert Gignoux as Thomas
Upon its theatrical release, Cousin Cousine received mostly positive reviews, both in Europe and the United States, where it became a surprise hit - the most popular French film in the US since A Man and a Woman.
The film was the 35th highest grossing film of the year in France with 1,161,394 cinema admissions.
In his review in the Chicago Sun-Times, Roger Ebert gave the film three and a half stars out of four, writing:
Cousin Cousine tells the story of an impossible love affair, and the two people who make it gloriously possible. That would be enough in itself—blind faith in romance is so rare these days—but for some lucky reason the movie gives us more. It gives us, first of all, one of the most engaging and likable couples in recent movies. It gives us a feeling of a real human milieu, of the families these people belong in. ... They dance, they tell each other little things about themselves and a sudden, healthy, sensual affection is born. ... There is no doubt at all, of course, that they're in love. But they don't sleep together for quite a long time, partly because what they have is so unexpected and precious that they want to savor it.
In his review in The New York Times, Vincent Canby called the film "an exceptionally winning, wittily detailed comedy that is as much about family relationships as it is about love." Canby goes on to write:
In a rather startling way, no one seems to get seriously hurt in this film, even though there are deaths and profound disappointments, not because Mr. Tacchella takes a superficially rosy view of things, but because, with the help of his actors, he creates a group of characters who appear either to have inner resources or, like Karine, to be too self-absorbed to feel anything too deeply. Miss Barrault, who is the niece of Jean-Louis; Miss Pisier, Mr. Lanoux and Mr. Marchand are very good company, especially when they are misbehaving. Cousin, Cousine possesses a heart that is both light and generous.1975 Louis Delluc Prize (Jean-Charles Tacchella) Won1976 César Award for Best Supporting Actress (Marie-France Pisier) Won1976 César Award Nomination for Best Actor (Victor Lanoux)1976 César Award Nomination for Best Film (Jean-Charles Tacchella)1976 César Award Nomination for Best Screenplay (Jean-Charles Tacchella)1976 San Sebastián International Film Festival Silver Seashell Award (Jean-Charles Tacchella) Won1976 National Board of Review Award for Top Foreign Film Won1977 Academy Award Nomination for Best Actress in a Leading Role (Marie-Christine Barrault)1977 Academy Award Nomination for Best Foreign Language Film1977 Academy Award Nomination for Best Writing (Original Screenplay) (Jean-Charles Tacchella, Danièle Thompson)1977 Golden Globe Award Nomination for Best Foreign Film1978 Kansas City Film Critics Circle Award for Best Foreign Film Won