This is a lean, taut suspense film--only 80 minutes long, and more than half of that is truly suspenseful and unnerving. There are only four actors in the movie, and they all do an excellent job of seeming like real people with real motivations, blind spots, and flaws. For the most part, writer/director Viljar Bøe does an excellent job of showing us things that don't quite make sense and convincing us that it's not necessarily irrational or unreasonable. He creates a feeling akin to being seduced into a toxic relationship, where in hindsight you realize how abundant all the red flags were but in the moment you're willing to rationalize and excuse every individual one. If this is allegorical horror, then its allegory is for the poor "NTA" victims on the Reddit thread "Am I The A**H***?", who post detailed narratives of having been gaslit by psychopaths yet seem totally clueless about the blame not being their own.
That said, once the mystery is revealed about midway through the movie, the movie does lose a great deal of its suspense as characters quickly devolve into horror movie stereotypes. While the second half is disappointing, it's not so bad that it brings the whole film down--plus, the final moments are fresh and surprising enough that they'll guarantee the film's haunting images will stick with you for a few days. On top of that, Bøe's writing wisely leaves a lot of backstory unsaid, leaving audiences with plenty of queasy questions that they won't want to think about the answers to. A lesser film would feel the need to tidy things up more.
I'd recommend this for anyone who's into disturbing thrillers. The strong acting, masterful editing, and original premise are enough to earn a solid recommendation, even if the final act doesn't fully live up to the movie's promised potential. I eagerly anticipate Bøe's next film.