Only the Brave(1994)

Alex is in love with her best friend, Vicki, her mother has dissapeared and she sets fire to things in her spare time. Vicki comes from an abusive home and wants Alex to run away with her. Alex is a bit of a nerd and a teachers pet, so takes advantage of this by trying to seduce her drippy school teacher. Alex watches as Vicki, unable to escape her terrible homelife and an psychological wreck, sets alight to herself and burns to death.