She's not an angel.
She's made mistakes.
She's not an angel because she has seen some shit.
She's not an angel because she has gone through what most people would consider a lifetime full of events in just a few years.
She's not an angel because she doesn't want to be. Being like an angel makes your life boring.
Being an angel would make your life so perfect you wouldn't have any experiences to tell.
Being an angel just wouldn't make her, her.
It would turn her into someone who had lost the potential to have been one of the few who could say they experienced life.