OK so I'm 19 now but I remember this movie about a girl or guy I think that goes to a ball or something and has someone with her and the guy with her is walking under this ladys dress I remember that scene

Then there is a scene where I think they are flying on a carpet underground and they come to this huge door and the guy tells the other person to open it and they say no and finally they do and this like monster thing comes out and they blame it on her when the guy really told her to do it

Another scene was a girl playing a harp in some big room