Sean Penn deservedly won an acting award at the Cannes Film Festival in May for his fearless performance as a troubled soul in the dark, downbeat melodrama "She's So Lovely."

But the rest of the film is the pits, with a story that romanticizes mental instability, as the deep love two people have for each other transcends everything else in their lives, including moral judgment.

Is this love or self-indulgence?

"She's So Lovely" is directed by Nick Cassavetes from a screenplay by his late father, Hollywood actor and avant-garde filmmaker John Cassavetes ("Husbands," "A Woman Under the Influence"). But it has none of the elder Cassavetes' dark-and-dirty charm or any sense of gritty reality.

The movie's first two-thirds revolve around young Eddie and Maureen (real-life marrieds Sean Penn and Robin Wright Penn), a pair of lowlife losers who supposedly love each other madly.

As the film opens, Maureen is lonely, unhappy and pregnant, and her punk husband Eddie has been gone for three days (not an unusual occurrence).

So, Maureen goes out and gets drunk with a neighbor (James Gandolfini), a boozy goon who rapes and beats her. When Eddie returns, Maureen tries to keep it from him, knowing he'll kill the guy if he finds out.

But during a brief sober moment, the wildly unstable and unpredictable Eddie figures things out and goes on a shooting spree and fires on an innocent medic. Eddie is immediately incarcerated in a mental facility.

At this point, the film leaps forward a decade, as we discover that Maureen has never visited, phoned or written Eddie. In fact, when he's released, Eddie thinks he's only been in the facility for three months because that's how long Maureen told him he'd be there.

In the interim, Maureen has somehow married wealthy, crass Joey (John Travolta) and settled into upscale suburbia, making a home for her three children — the oldest being Eddie's daughter.

As the final third unravels, Eddie and Joey argue over Maureen, who says she has told Joey all along that when Eddie got out she'd be running off with him.

On the surface, this is a typical John Cassavetes family dynamic, and it provides the basis for what could be an interesting story. But it feels incomplete, as if the Cassavetes had put the screenplay in a drawer with intentions of finishing it later. The characters are skimpy, none of their behavior seems grounded and many plot points are unlikely at best.

Worse, no one here is in the least bit sympathetic — except the children, and you might feel they would be better off in a foster home. We are supposed to believe that Joey and Maureen have been happily married for nine years, but there's no evidence of that. They fight, drink and carry on, without the affection we witnessed between Maureen and Eddie.

The star casting does help. As mentioned, Penn is tops, and Travolta works hard at his underwritten character. Robin Wright Penn is less effective, however, delivering an unpleasant one-note performance. Gena Rowlands (John's widow, Nick's mother) has one scene but little to do.)

On balance, a misfire that doesn't live up to Nick Cassavetes' promise with his first directing effort, "Unhook the Stars."

"She's So Lovely" is rated R for wall-to-wall profanity and vulgar language, violence and rape.