Originally Posted by
Settiesama
It's stated in the book that dragons take consorts as more of a spiritual and emotional bond, it doesn't mention anything on physical though. They seek a connection with a partner on a level that the land (for lack of better words) races can't comprehend. That is why Tiamat freeing herself is a highly unlikely event, as more than just creating a monster of a thing named after Bahamut, she feels she betrayed that bond they had, which if is something we can't even imagine, is understandable why she would never want to leave or even die in the prison.