"We Don't Live Here Anymore" is like the bad fight that ends the bad marriage: ugly, messy, loud, sometimes incoherent, but ultimately necessary. You're glad when either of them -- the marriage or the movie -- is over.

Adapted from two short stories by truth-teller Andre Dubus, the movie is about adultery among the assistant professoriate. It gets the incidental anthropology perfectly: the messy Arts and Crafts bungalows, crammed with books and wine bottles, where our characters live; and the mismatched clothing worn by people who read Tolstoy but not GQ.

Having evoked effortlessly that world by superb scene and costume design, the film then watches as two highly verbal and overly intelligent couples fight, cheat, regret, lie, try to pick up the pieces, act abominably, drink too much and get on with their lives. Watching the movie is like having dinner with two George-and-Marthas from "Who's Afraid of Virginia Woolf?" and you might ask: Why put yourself through it? The answer, I suppose, is that although the truth hurts (even if it's other people's), it's still the truth.

Jack & Terry & Hank & Edith -- who could not call them that? -- live somewhere in Washington state, and Jack & Hank teach in a small college's creative writing department. Hank (Peter Krause of "Six Feet Under") still wants to publish. Jack (Mark Ruffalo) appears to have given up, and his writing consists of scrawling the word "Awkward" on student manuscripts. The two may be experts on creative writing, but they know more about creative loving, as each is having an affair with the other's wife and, though it is unsaid, each of the four either knows or suspects the truth.

The problem isn't really sex. As Hank says, "Everyone deserves to be happy," meaning that no one in this menage a quatre appears to begrudge his or her official spouse an unofficial roll in the hay now and then. The problem is love.

As Charles Bukowski said, love is a dog from hell, and its assault pretty much tears these poor folks apart. The most destructive love is Jack's for Hank's wife, Edith. Jack wants not just the pleasure of the new body but the lasting joy of finding the soul mate. He no longer loves his wife, Terry (Laura Dern), and has given himself over -- the longing looks, the trysts in the woods, the feeble, ever-mounting edifice of lies necessary to sustain the relationship -- entirely to Edith (Naomi Watts) instead.

Hank, for his part, no longer loves Edith, or at least no longer desires her, because he's upset with his inability to publish. Edith feels distraught at her disconnection from Hank and has thus given herself eagerly to Jack, although it's unclear whether the sex or the love is more important. Terry is so furious at Jack, she has sex with Hank to get even.

Oh, and they all love their kids.

And just to make it all the more tangled, they really like each other a lot.

Directed by an Australian named John Curran, who has only one obscure feature on his resume, the film astutely finds a vivid personality for each character. The intricacies of who's mad at whom when and why and who has just slept with whom or planning to sleep with whom might not be worth chronicling in any depth, but the characters are. Krause's Hank is the most laid back; he's a man of repose, quiet irony and even quieter despair. I don't think he ever raises his voice, and his most conspicuous trait is a kind of smug refusal to be surprised by anything the world is capable of conjuring for his ironic examination. Meanwhile, Watts's Edith is sexually greedy, open, funny and strangely untroubled by the situation. Possibly she comes from wealth, for her house is much nicer -- I'd guess it has been professionally decorated -- and she drives a Mercedes-Benz station wagon that has to be beyond an assistant professor's salary. She's like Daisy Buchanan, sloppy and numb, without much in the way of self-awareness.

Ruffalo's Jack is all fidgets and sensitivity. This actor can be annoying in his occasional attempts to out-Sandy Dennis Sandy Dennis, but here he keeps his twitchiness, the odd pauses and clumsy gropings of his line readings under control. Poor Dern has the least attractive role; her Terry is semi-alcoholic and riven with fury. Her beauty is almost always banished by her anger, which clenches her mouth into an eternal sneer, out of which pours the most vicious, but never unjustified, venom.

The movie never builds any particular dramatic momentum; like life, it's anti-dramatic, and you know that these marriages probably can't be saved. It drifts toward unsatisfying resolution, without the kind of Big Movie Moments so popular in the summer. In the end, it merely says: This is how it was, this is what it felt like, this is what happened. That's more than enough.

We Don't Live Here Anymore (104 minutes, at Landmark E Street Cinema, Landmark Bethesda Row Cinema and Loews Cineplex Georgetown) is rated R for sexual situations and profanity, as well as ugly emotional confrontations.

Laura Dern, above left, and Naomi Watts play campus wives having affairs with each other's husband in "We Don't Live Here Anymore." Dern, whose Terry is married to Mark Ruffalo's Jack, left, is saddled with the least attractive role: a semi-alcoholic character riven with fury.