Personally, I don't think she'd be happy in a castle. She was okay in the tower, but she obviously didn't like it very much. Punz needs freedom, and she knows how to care for herself, so having people wait on her for her whole life, I don't think she'd like it much.
And I really don't think she would have put up with being forced into marriage. She would have run away a looong time ago if she was.