Be My Star

Be My Star is an Austrian-German drama film, directed by Valeska Grisebach and released in 2001. The film stars Nicole Gläser as Nicole, a teenage girl in Berlin who is beginning to establish her independence by entering a relationship with Christopher, with whom she begins to imitate the rituals of adult relationships by having a mock wedding and acting as a married couple when their parents aren't around.

Synopsis from Wikipedia, CC BY-SA 4.0. Everything below written here.