Girls are mean, get over it.

You landed a costume design gig at an art highschool, and now you are surrounded by a small group of people who have known each other for years and don't need any new friends. This is not a primo-bonding situation, but you come in contact with a girl who is at least as bitter at having to be alive as you are. No one mentions to you that two angsted people can only be friends as long as they can bite their tongues, but you find out soon enough.

Until then, you take microdot and smoke cigarettes in her basement room, eating the expensive cheese her parents can afford to buy and talking trash on all the stuck-up music theatre kids. Of course the falling out happens over a boy, and of course none of it is worth your time save for the sociological intrigue of it all.

Wait, what did you do to piss her off?
Get over it and out of highschool.