I agree with your whole post.
One thing though, this may be a girl that has no remorse. The things she did weren't normal for ANY age girl with a good family. Oh, dating an older guy and going behind her parents back is nothing new.....but knowing the guy had guns, watching him murder her parents THEN taking off with him.......NOT NORMAL>
A NORMAL person would have run AWAY from danger. She ran towards it. She may be one of those people that don't have normal emotions and/or feelings. I don't care how much she thought she loved the guy. Knowing he killed them should have sent shockwaves thru her: "DANGER DANGER"
And the B.S. that maybe she went with him to get him away from her siblings......yeah, right.
She didn't call 911 or run to the neighbors to get help for her bleeding & dying mother & father.