Just Ella by Margaret Peterson Haddix published by Aladdin (1999) [Paperback]

It's a familiar story: In spite of the obstacles put in her way by her wicked stepmother, Ella goes to the ball, sweeps Prince Charming off his feet, and is chosen to be his bride. Now she's comfortably ensconced in the palace, awaiting marriage to the man of her dreams. It's happily ever after time, right? Wrong! Life for fifteen-year-old Ella has become an endless round of lessons and restrictions; even worse, Prince Charming turns out to be more like Prince Boring. Why can't she talk with him the way she can with Jed, her earnest young tutor? Slowly, Ella comes to realize she doesn't want the life she fought so hard to win. But breaking her engagement proves more difficult - and dangerous - than escaping her stepmother's tyranny.