There are some good movies about breakups (Woody Allen's Annie Hall, Albert Brooks' Modern Romance) but not many where the breakup is amicable. The essence of storytelling is conflict, so someone needs to be unhappy before the happily ever after.
In the case of Celeste and Jesse (Rashida Jones and Andy Samberg), the unhappiness belongs to their friends, who can't understand how the couple can laugh, love and live together several months after agreeing to a divorce.
Celeste is a successful marketing executive. Jesse is an unsuccessful artist who sleeps in the studio of the Los Angeles home they share. He's more than a little lazy, but in the secret, silly language they share, Celeste can vent her frustrations about clients such as pop tart Riley Banks (Emma Roberts). So when Jesse meets Belgian beauty Veronica (Rebecca Dayan), Celeste finds herself jealous.
While Celeste fends off a suitor of her own (Chris Messina as a nice guy from her yoga class with whom she has little in common), she tries to prepare for the wedding of her best friend (Ari Graynor) but goes into a tailspin co-piloted by her pot dealer (Will McCormack, whose brief real-life relationship with Jones became the basis for their script).
Jones has been an engagingly patient co-star in comedies such as I Love You, Man and The Big Year and in the TV series Parks and Recreation. In her first starring role, Jones is self-effacingly funny in a Kristen Wiig way without down-playing the intelligence she showed in The Social Network. By comparison, rubber-faced Samberg is irritatingly broad, although the character does grow when he's presented with a sobering challenge. Likewise, Roberts evolves from a cartoonish teen queen to something like a real person.
To its credit, Celeste and Jesse Forever wants to be more than a formulaic farce. It succeeds to the extent that the neighbors keep up with Jones.