You are right about the parental aspect. That should be taken into account when the OP makes her decision how to proceed because it sounds like her boyfriend needs a parental figure(or a way of accessing one inside himself) right now more then he needs(or can handle) a lover.
On the other hand, I was not saying she should treat her boyfriend like a child and make his decisions for him but instead function as a model for more appropriate behavior while stepping away from controlling or taking responsiblity for her boyfriends decisions. (Now that he is percieved as an adult, this is a very difficult position for a person to be in--since no one really can take responsiblility for his actions except for him--not like a parent can for a child. What he really needs is proper parenting. But he cannot go back in time and get that. Nor can she provide it, she can only model the _product_ of proper parenting and hope he catches on. Frustrating!)
Perhaps using the word parent to describe the process was not the best choice. And the suggestion of getting a therapist or outside authority to help as a parental model is really good.