The Butterfly (2002 film)

The Butterfly, or Le Papillon in original French, is a film by Philippe Muyl starring Michel Serrault and Claire Bouanich.

It all ends very happily as Julien is released when they realize that he had never kidnapped Elsa. Isabelle, Elsas mother, allows her to continue seeing Julien and studying butterflies with him. Both Julien, Elsa, and her mother benefit greatly from each others presence.

Source: Wikipedia