Why does one feel bad?

That is probably the underlying reason why she flipped out cuz she doesn't like him, thus doesn't trust him. You are probably very special to her and she is over protecting you. Tell her very specifically timewise next time when the movie will be out or exactly what time you want her to pick you up, etc. Try to make her happy even tho she is overreacting. Making her more angry will only make the situation worse.