Because

"Tanja and Martin are a couple in their late twenties. They meet back at their apartment late one evening, in bed. Weren’t we supposed to meet up this evening? How come you got home so late? Where the hell were you? An argument ensues, an everyday fight between couples that unleashes an unimaginable destructive force. Three separate variations of the argument are played out. Each time the positions of culprit and victim, guilt and innocence, trust and despair are reversed."