Available on DVD: “Keep the Lights On”

When we first meet Erik (Thure Lindhardt), a Danish filmmaker living in New York in 1997, he is on the telephone looking for a casual sexual hookup. He seems fickle and impatient, hanging up on potential partners at the first hint that the chemistry might be wrong, but eventually he finds more or less what he is looking for. Quite a bit more, actually, in the person of Paul (Zachary Booth), even though Paul says he has a steady girlfriend, and Erik is not interested in commitment.

Fate — or whatever force governs the erotic destinies of modern city dwellers — has other plans. Keep the Lights On, Ira Sachs’s sensitive, knowing new film (his fifth feature), follows Erik and Paul for more than a decade, during which their relationship blossoms, withers and renews itself like a perennial flower with a peculiar and unpredictable life cycle.

The physical attraction between them is strong and immediate, but they don’t necessarily seem like a promising couple, and not just because Paul is ostensibly straight. That is a minor detail in the greater scheme of things. The more significant obstacle appears to be a temperamental difference.

Erik, who has been desultorily working on a documentary about an avant-garde New York filmmaker, is something of a flake in work and love. His best female friend (Julianne Nicholson) worries indulgently about him. His sister (Paprika Steen) scolds him about his lack of direction, warning him that being "up and coming" is not an appropriate condition for a man in his 30s. With his gap-tooth smile, laid-back posture and unkempt blond hair, Erik seems locked in perpetual, irresponsible boyhood.

Paul, in contrast, presents a more conventionally grown-up face to the world. He is organized, ambitious and professionally well-established, with an important job in book publishing. But one of the most ingenious and convincing aspects of Sachs’s film is the way it allows the characters to move in surprising directions, upending our expectations and their own sense of who they are, individually and to each other.

So it is Paul who proves to be the wayward soul, in danger of losing everything — Erik, his job, his life — to drug addiction. And Erik, at first glance a freer, more hedonistic spirit with a wandering eye and an eager libido, turns out to be a more disciplined and steadfast fellow than anyone might have supposed. He grows out of his dilettantism and promiscuity even as Paul slides perilously in the other direction.

This summary — and I have only sketched the outlines of a wandering, episodic story — makes Keep the Lights On sound much more schematic, more like a morality tale, than it really is. Its subject is not addiction or ambition, or even love in a conventional romantic sense, but rather the more elusive and intriguing matter of intimacy: how it grows, falters and endures over time. The dialogue sometimes has a canned, hectoring sound, as if the actors had been called upon to announce their feelings rather than express them, but the look, mood and rhythm of the film are exquisitely, even thrillingly authentic. In scenes that jump from year to year and linger over significant, ordinary moments, Sachs captures the ways strangers turn into lovers and the equally scary and exciting ways that lovers can remain strangers.

In its commitment to candid, sympathetic emotional exploration, Keep the Lights On invites comparison to Andrew Haigh’s Weekend, perhaps the best big-screen love story — gay or straight, vampire or human — in recent memory. That film seemed to telescope a universe of romantic possibility into a single 72-hour stretch, during which a one-night stand between two young British men grew into a profound, life-altering and yet still elusive connection. Sachs takes a longer view, but the films share an interest in mapping the nuances of feeling that arise between men for whom sex is the easy part. They also both examine the complexities of gay life at a time when closets have (mostly) emptied, the threat of AIDS has (largely) diminished and the tide of intolerance has (significantly) receded.

The richness of Sachs’s accomplishment lies in the sense of familiarity he creates, the implicit bond that develops between the couple on the screen and the people in the audience. Even more than Forty Shades of Blue and Married Life, his two most recent films (both well worth renting if you haven’t already), Keep the Lights On feels as if it’s about people you know. I don’t mean that Paul and Erik are recognizable types — since I’ve never met a Danish documentary filmmaker, I couldn’t really say — but rather the opposite. They are so real, so specific, that by the end of the film you feel implicated in their lives, close to them precisely because after all this time, you still don’t understand them completely.