Am I being manipulated by my girlfriend?

A few hours ago, I (16M) went to my girlfriend's (16F) house determined to be sincere with her, about not being comfortable with our relationship, and how I don't see her as my future wife, therefore not confident of planning my future with her; just my feelings. The conversation became too emotional, both of us cried and she kept trying to reverse the situation, saying that I'm feeling like this because I want to, and that I'm not letting myself try to fix the situation. The fact is: this is not the first time. I've been feeling this for a very long time and for like three times tried to tell her this, despite she saying the same thing. She simply can't let me break up with her, she doesn't accept it. The worst thing is that now I will continue to have this feeling and that she doesn't respect my decisions, which affects directly my honesty with her. Am I really being too restrict or is she manipulating me?