Froschkönig (1988)

Henriette is a princess; she is playing with her ball, but drops it into a well. A talking frog replaces it with a golden ball, on condition that he can eat and drink with her, and rest in her bed. She accepts, but then is repelled at the thought of the frog eating and drinking with her, etc, but her Father makes her do so. In her bedroom, the frog turns into a handsome prince, and she falls in love with him, but he leaves immediately becasue of her broken promises. She pines and eventually seeks him out, braving various tests of her truthfulness in the process.