"The One I Love" is one of those movies that you're better off not knowing very much about before you watch it, but my enjoyment wasn't hampered at all by knowing a few minor facts about its nature going in, so I'll describe the story in broad terms, and you can stop reading at the end of this paragraph if you don't want to know even that much. I did enjoy it very much, with special kudos to the complex performances by Mark Duplass and Elizabeth Moss.
Sophie (Moss) and Ethan (Duplass) are a couple with a relationship in crisis. They visit a therapist (Ted Danson), who suggests that they take a vacation together to a secluded retreat to try and rekindle the romance. The trip forces the pair to confront themselves and each other, and question the nature of their attraction and commitment. At this point I should mention that "The One I Love" is a genre film - not a science-fiction horror thriller or an action spectacle, but the kind of quieter, more thoughtful small-scale genre story that might be mistaken for one of the more charming, low-key episodes of "The Twilight Zone." This is an absolutely no-frills production, with only three actors that ever appear on screen, one major location, and clearly not much of a budget to speak of. However, first-time director Charlie McDowell does a lot with a litte, neatly juggles some very complicated scenes, and it never feels like any corners are being cut.
Mark Duplass is one of the central figures of the mumblecore film movement, and much of the dialogue in "The One I Love" was reportedly improvised by him and Moss. However, the film is too polished and too precisely plotted to qualify as a true mumblecore piece. There's a wonderful sense of spontaneity to it, though, and the actors do a remarkable job of showing us all the ins and outs of Ethan and Sophie's relationship as it teeters on the brink. The genre elements that come into play are handled well, and the central "what if" is a fascinating one. Still, the movie is better when it's focused on the performances rather than the plot. The ending is also much too pat and predictable, but it's one that works in context.
I especially enjoyed the pairing of Duplass and Moss as our dysfunctional couple. I've been a fan of Duplass's onscreen work for a while, but this is the first time I've seen Moss in a feature film in decades, and she's excellent. Once she's done with the last season of "Mad Men" next year, I hope she gets the opportunity to do more work like this. The unusual premise demands a lot from the performances, very nuanced behaviors and interactions that I haven't seen many actors pull off so well. Moss gets some fun ambiguities to play with, and Duplass nails being that guy who thinks he's smarter than he actually is.
This is the kind of high concept, low-budget film that has benefited so greatly from the descending costs of special effects, though the use of them here is very restrained. Independent filmmakers are making the most interesting genre pictures these days, because the ideas and implications of the extraordinary can take precedence over the spectacle. "The One I Love" is the perfect example, a movie that takes an intriguing hypothetical and lets it play out thoughtfully and relatably on a human scale. It's so well grounded, I think it's a genre film that would work for people who generally dislike genre films. And it's one of the best films about relationships I've seen a long time.