What is this movie...?

It's about a woman who seems to be able to control ice, perhaps an ice queen. The setting is a cold, icy place and this said woman seems to be in love with a man whom is already in love with someone else. A human. So this 'ice queen' keeps him locked away with her but in the end I think she lets him go so he can be with the one he loves. I saw an AMV about it once and it seemed really good. If anyone could help me out it'd be much apperciated.