Had it kept prodding at the political parallels of 1990 Berlin and Maria and Henner’s romance, “Someday We’ll Tell Each Other Everything” would have sat beautifully at the intersection between the coming-of-age of a young woman and that of an old country. Instead, Atef opts to stretch out the story, stubbornly tugging at the corners of the narrative, expanding a tale rich in its metaphors until it becomes see-through.