Spoiler Warning. If you have any intention of seeing this film, go ahead and do so before reading beyond the first paragraph of this article. This is not just my reccomendation - this was the main message given to the press upon this film's release last year, promising a provocative twist on an otherwise run-of-the-mill story about a couple - Ethan (Mark Duplass, Jeff, Who Lives At Home) and Sophie (Elisabeth Moss, Mad Men) - who go away on a retreat to try and rekindle their marriage. The promise of such a twist has been so woven into the film's marketing blurb that it's almost certain to result in disappointment from some viewers, but I certainly wasn't one of them, as much as I think the film needed some fine tuning on its Charlie-Kaufman style plot. Remember, spoilers from now.
Ethan and Sophie have been failing to rekindle their relationship, unable to develop their relationship beyond their initial spark of passion and now reaping the unhappiness from having not moved it forward. Their new marriage councillor sends them to a retreat which seems normal at first, until both of them experience things with the other that their spouse does not remember. It seems that when one of them enters the property's guest house, they are able to interact with a doppelgänger of the other, with certain things refined and improved - Sophie's doppelgänger cooks fried breakfasts for her husband, and Ethan's is sensitive and works out. Things take a strange turn when both doppelgängers are able to leave the guest house, spiralling the film out into a bizzare sci-fi-lite plot in which it's revealed their copies are people conditioned to be like them in order to escape the house. It all gets confused from that point, until the real Ethan escapes with the woman he believes to be his real wife - and we are left to wonder whether he is right.
I wouldn't usually put focus on a film's advertising, but the director put so much PR into the preservation of a spoiler-free experience that one must wonder where that's coming from. The One I Love's concept is something out of a Twilight Zone episode (indeed, that show is name-dropped) and the film doesn't really drop its big "twists" until about two-thirds of the way through. If you accept that McDonnell just wanted to preserve the first time experience (despite living in this age of digital free information), then it was a poor decision - said third-act twist is poorly explained and not really elaboated on - and that's okay for the purpose of the movie, it's just not something to get hyped up over. A more cynical view is that the whole thing was a marketing plot to allow the film to be advertised as a more mainstream romantic comedy instead of the quirky pseudo-thriller that it is.
All that makes things a little awkward from the off, because despite that little bit of strangeness in its marketing, I really love this film. Duplass and Moss carry the film for pretty much its entire runtime, and play two characters who are subtly the same but different. Moss especially manages some Tatiana Maslany style subtlety whenever she gets to play her doppelgänger (mainly near the film's end.) On a textual level, The One I Love captures the necessity of renewal in long-term relationships, with both characters defeated by their inability to compromise and work towards maintaining their relationship as both of them change and grow older. If the final scene's suggestion is to be believed, then Ethan can never learn his lesson, because he now lives with a version of his wife who will change to acquiesce to his desires, and by pursuing Fake!Ethan, Sophie is now trapped in the estate for some unknown amount of time, possibly for the rest of her life.
The supernatural idea that defines the first half the of the movie becomes its main flaw when they try to explain it - as a plot device it just exists, but the moment you try and explain its mechanics in real-world terms you start to strain suspension of disbelief. A doppelgänger producing house in the middle of nowhere is a random supernatural occurrence. Introduce elements of conspiracy and secret files and a strange, lethal force-field, and you start wanting to put people behind their existence. And the film doesn't need that, because as it stands its a good enough exploration of the central relationship. If you've not seen the film and you read this far anyway just to defy me (it's okay, I still love you, reader), go and see it. There are a few shots that linger for too long and all over the direction could have some fat cut away from it, but as an experience it's still a fantastic rollercoaster with a fairly decent message behind it.