SALT LAKE CITY, Utah — Celeste and Jesse Forever is a modern movie about letting go that can be funny, cute and awesomely sad all at the same time.

The two title characters are best friends and high-school sweethearts who got married young. The movie’s photobooth of an opening (set to Lily Allen’s “Littlest Things,” in an act of soundtrack foreshadowing) takes us through their timeline, and in flashes we watch their perfect relationship devolve.

But when the dialog begins, everything seems normal. Their easiness around each other, weird inside jokes and obvious mutual adoration make them the couple everyone else hates. This is when we, laughing with a tinge of jealously, learn that they are getting divorced — and that things have never been better.

In an hour and a half, Celeste and Jesse, or Rashida Jones and Andy Samberg, are forced to confront the fact that the idea of a simple divorce and continued closeness is impossible, and that moving away from their comfortable rapport is inevitable.

Coming to terms with a new life without Celeste, or perhaps anyone, is faced head-on by Jesse. He states his feelings outwardly, cries frequently, and in the beginning is certain this split is just a phase. Samberg does a good job in the more serious scenes, but still manages to get through it all with his brand of humor — without his usual Saturday Night Live gimmicks.

He was scared to start all over again, he confides in his pot-dealing friend (played by Will McCormack, co-writer of the film), confronting the fear that keeps many couples together.

The film, which premiered over the weekend at the Sundance Film Festival, was co-written and co-produced by Rashida Jones, whose Celeste is possibly the best role the actress has ever had. A successful thirty-something, Celeste seriously struggles with showing weakness and being wrong (splitting up was “right,” so she has to pretend to be fine with their current arrangement, though clearly she is not). The emotional toll of the divorce creeps up on her slowly, then hits her dramatically.

Celeste’s struggle with facing her mistakes, regrets and true feelings about losing Jesse is what really drives the movie. She’s cold, self-righteous, self-involved and totally messed up, but she is endearing and relatable in a funny but cringe-worthy “been there” sort of way. Jones’ performance stands out as the strongest of a good cast — she’s messed up, but honest.

As Jesse and Celeste drift apart and come back to each other over and over, in an unhealthy but realistic look at how hard it can be to let go, they grow up. And friends Beth and Tucker, Celeste’s gay business partner (Elijah Wood), and their tarted-up pop-star client Riley (Emma Roberts), help them along the slow and agonizing path to being OK.

The script is quick and sharp, and seriously funny at times, but with emotional maturity: Here’s real heartbreak, and here’s how we survive it. Directed by Lee Toland Krieger, the film finds a way of telling a story that seems familiar but evolves into something new. The depth of the characters makes their twisted, insecure attachment so compelling, their love real, and their comedy so infectious. In this way, the movie succeeds where many others have failed.

The snap reviews on Twitter following the movie’s Friday night premiere in Park City were fairly mixed, but it appears this movie has real mass appeal: Saturday night’s screening at the Rose Wagner Performing Arts Center marked the movie’s first showing to non-industry types, and the room was roaring with laughter (and occasional sniffles).

As part of Sundance’s Premiere category, and featuring a well-known cast, the film is likely to be picked up by a studio pretty quickly — probably bound to be marketed as a rom-com, when it’s ultimately not that type of film. It’s a movie about letting go, and finding the courage to start over. It’s about real life, taken from real experiences, and contains real emotional complexity that many can relate to.

Celeste and Jesse Forever leaves us with this good takeaway, as told to Riley by Celeste: The pain from relationships never gets better, but we do.

WIRED Honest, complex and sharp script is executed perfectly to make this a hilariously sad but introspective anti-romantic comedy.

TIRED Depending on your past life experiences, this movie can seem either really short or realllllly long.