Just Ella By Margaret Peterson Haddix?

I really didn't like this book. It is the sequel to the fairy tale Cinderella. It's about Ella living in the castle and really not liking living there. She reveals that she doesn't have a fairy god mother like people say. She finds the prince dull and boring. Then she falls in love with someone else. The part I don't get is when one of the evil stepsisters marry the prince. In my opinion it's a very bad book.