The Fan (1947)

Martine is a lonely girl in an exclusive boarding school who conjures up a glamorous existence in order to make her dull life tolerable and to impress the other girls. One of her flights of fancy is a love affair with Brevannes, a famous composer. She leaves the school and goes to the French Alps to find the life she's only dreamed about, where she meets Brevannes and a December-May romance develops until she meets a young mountain guide, Henri Vidal.