Maybe it would help to think of it like this.... The adolescent brain is changing the way all the nerves link, and the other time changes like this happen is when children are about two years old. We understand two year old not coping... But often still expect the teen to be able to manage the emotions. She can't. Perhaps if your default message or the comment you make is "it really sucks when you can't get what you want" or "when things don't go how you expect" or something... Said in a genuine non confrontational calm way.... She can't argue cause you are sympathising with her. Maybe that's an idea??