what rights does she have?

My friend and her boyfriend wanna get engaged, hes 17, shes 16, her dad is a cop and her parents are separated, she mostly lives with just her mom, her mom knows about her bf but her dad doesnt, if shes getting engaged, does she have any right to overpower the system? Like does that eliminate all the parents rights of her? Or does she just have to not do anything till shes 18? Could she start sleeping at his house and stuff like what rights would she have in the state of Pennsylvania? (Idk if its different in each state)