The theme of love and farewell, varied in the relationship between young and old couples, seemed appealing to director Wolfgang Hübner. To make it believable, he needed two very young amateur actors. He searched for Katrin and Frank for three months. Ten were shortlisted from hundreds of applicants. He then decided on Birgit Käding, a 15-year-old schoolgirl, and Sven Martinek, an 18-year-old apprentice. Neither had applied for the role. Birgit was discovered in the ensemble of the "Haus des Lehrers" (House of the Teacher) in Berlin. She immediately brought what the author Günter Görlich and the director expected from Katrin: depth of feeling without sentimentality, strength of will and reserve, charm and a little cheekiness.