Jessica It was because she was making an intentional sacrifice in order to protect the safety of her country. She was willing to sacrifice what she really wanted (to marry Char) because of the danger it could put so many people in.
This answer contains spoilers… (view spoiler)[It wasn't just that she was mad about being given an order; it was that she was being forced to marry Char when she feared her curse would make his life dangerous. Her curse broke because she refused to obey an order not because she didn't want to do it but because she feared for the life of the man she loved. (hide spoiler)]
Eve She broke the spell by doing it for someone besides herself. She was making a sacrifice by not marrying Char because she feared it would hurt him, make his life dangerous. By denying herself she thing she most wanted to protect someone else she broke the spell.
Emily Savage She wasn't really mad. She broke the curse to protect the man she loved by possibly dying because of her.
Chickensplat this was so much more than just being mad! it was her rebelling, and her love that broke the curse not just getting mad. gosh that sounded so cheezy
Serena Taylor It wasn't anger that broke the curse. I guess you could say it was love. The only way to save the prince was to break the curse and she did. because of her determination, she was able to resist the effects of the curse to the point of it breaking.