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Saw this in the late eighties.
Boy escapes the grasp of an all female command and having been misled to believe a holocaust type scenario joins with a girl.
They work their way through a series of rooms. The final scene, I remember, involves the boy slicing the wall with a knife to reveal sunlight and sand (beach or desert).
It was a false lie in a totalitarian underground cult. I believe it was subtitled thus foreign.