This may just be my interpretation in relation to myself and my relationship, but I think it's about being naive and hoping for something that just isn't there. She clearly cares for this boy and wants him to be the one, her "knight in shining armor," but he doesn't treat her like she deserves and she comes to realize that he isn't what she thought or hoped for at all.
This may just be my interpretation in relation to myself and my relationship, but I think it's about being naive and hoping for something that just isn't there. She clearly cares for this boy and wants him to be the one, her "knight in shining armor," but he doesn't treat her like she deserves and she comes to realize that he isn't what she thought or hoped for at all.