As the opening credits display in John Curran's drama "We Don't Live Here Anymore," two couples mingle in a silent dance. It's an appropriate beginning for a movie that's, essentially, a melancholy change-partners dance, and a reflection on two marriages gone stale. And that choreography is given grace by four splendid actors, each of whom contributes a rich portrait of a troubled husband or wife who looks at the head on the other pillow and wonders where things went wrong.

As we gradually sort out the players (Curran and screenwriter Larry Gross, wisely, let us wonder for a while who's married to whom), the film's mood of simmering, painful honesty takes shape. Jack Linden (Mark Ruffalo) is a literature professor at a New England college. He and his wife, Terry (Laura Dern), have had a longtime friendship with writing professor Hank Evans (Peter Krause) and his wife, Edith (Naomi Watts) — meals and movies, glasses of wine and companionable talks while the kids play in the next room.

But this two-couple friendship is infinitely more complicated than those cozy dinners would indicate. Jack and Edith are having an affair; Terry suspects but isn't sure; Hank knows but, obsessed with his own problems (he's got writer's block and has grown emotionally distant from his wife), doesn't much care.

Movie review Showtimes *** "We Don't Live Here Anymore," with Mark Ruffalo, Laura Dern, Peter Krause, Naomi Watts, Sam Charles, Haili Page, Jennifer Bishop. Directed by John Curran, from a screenplay by Larry Gross, based on the short stories "We Don't Live Here Anymore" and "Adultery" by Andre Dubus. 103 minutes. Rated R for sexual content and language. Seven Gables, Uptown.

Curran zigzags from Jack and Terry's messy home to Hank and Edith's perfectly ordered one, contrasting two very different paired lives. Terry, desperately trying to regain control of her household, wants to create a life more like the calm Evanses — she attacks the laundry, offers lobster dinners, tries to smooth out the disorder. But she and Jack always seem to end up shouting at each other — her face tear-streaked, her frightened eyes indicating that what she's looking for is lost for good. "Other husbands," she tells Jack, heartbreak in her voice, "touch their wives."

Meanwhile, Hank and Edith barely speak, living quietly side-by-side. And the four form other pairings. Jack and Hank take jogs together, chasing each other (or so it seems) on a wooded trail, and hoist a few beers afterward, talking in circles about love. (Hank, played with angry detachment by Krause, enjoys playing games with Jack, never quite letting the other man know that he knows about the affair.)

Terry and Edith's friendship continues, with an unspoken strain. And Hank's eyes finally do land on Terry, leading to the final steps in the dance.

"We Don't Live Here Anymore" is a very talky movie, and occasionally an oddly dated one. (The Andre Dubus stories on which it's based date from the '70s, and while the movie's settings and costumes feel contemporary, there are a few anachronisms, most notably the burning of a manuscript. Wouldn't it be backed up on a disk somewhere?) But its performances stay with you — particularly Watts' angelic expression when she tells Jack, "If I didn't love you, I'd have to love somebody else," Ruffalo's sheepish smile as he finds not-quite-amusement at something that isn't there, and most of all Dern's ravaged face and emptied-out despair.

The Evans and Linden marriages may be fatally ill, but the art of screen acting is alive, well and cause to celebrate.

Moira Macdonald: 206-464-2725 or mmacdonald@seattletimes.com