It hurts to be tossed aside when you don't try hard enough for a 'friend' to be satisfied. It hurts to feel like you are nothing because your 'best friend' completely ignores you, then pushes you around if you don't fight.
that kiss was the best thing she'd ever experienced. nothing ever even came close. not the rush of fighting crime, not the power of her rituals. and thats what made it so painful- thats what broke her heart. and yet she stayed for as long as she could. until she started causing problems.