A troubled couple vacate to a beautiful getaway, but bizarre circumstances further complicate their situation.
Why it is hard sci-fi
A couple in marriage counselling are sent to a weekend retreat where each guest house contains a copy of the partner that is whatever the other partner most wants. The film commits to the rule. The copies are local to the guest house. They cannot leave it. The science is stripped down to a single mechanism and the film stays inside the rule for the rest of the runtime.
Science inside it
No claimed physics. The retreat operates as an experimental psychology setup with one impossible affordance, and the film follows the consequences. The interesting work is not in the mechanism but in the ethics of preferring an idealised copy to a real partner, which the film puts on screen as an experiment with a written debrief.
Spoiler alert
The therapist running the retreat acknowledges the mechanism only obliquely and the final scene leaves the original couple uncertain whether the partner they leave with is the real one or the copy. The film commits to that ambiguity rather than resolving it.