If atmosphere was enough, this would be a good film. The central character, a bereaved mother, is played with extraordinary depths of anguish; her lover clearly treads on eggshells around her, caring sincerely but fearful of triggering a meltdown.
The third main character, an architect, never seems to fit. Baffled by his circumstances, his response doesn't quite ring true. His link to the couple is unclear, as is the series of events that led to his current predicament. This is the film's weakness.
Two other characters - one seen, one heard - might as well not be there. The story was recorded long before Covid but could easily have been made without human contact but for the central couple.
While drawn absolutely into the mother's pain and guilt, I was ultimately left with no idea where it came from, whether it was deserved, or how it related to the other characters. A bravura performance in a B-movie, like an Oscar winner advertising toothpaste.