Žabí princ (1991)

When a young princess, instead of being fully dedicated to her love, persists in running around like a tomboy and roaming the forests with her gang, and a young prince refuses to give up all his vices and mischief, an aquaphobic fairy takes their fate into her hands. The princess then falls in love with the prince, who declares eternal fidelity to her. When he however breaks this promise, the fairy turns him into a frog. With which the loyalty of the princess is being tested as well.