Not being romantically or sexually interested in you is just a lot of words that describe "friend zone."
Anyway, I think you should stop hanging out with this girl and concentrate on being the best you that you can be by taking course, keeping your nose clean (juvi hall? come on dude) and getting a good job where you'll have less time to think about some chick. (whether you've been friend zoned or not).
Work on you. If you're not always fawning over one another in this pretend platonic thing (platonic on her part anyway) you've been carrying on in for far too long, then you'll probably start to see other girls that are available to be with you in a romantic sense as more attractive. Right now you've closed yourself off to other girls in heart and mind. What a waste of your dating years, son.
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BTW, Op: "Ladder Theory" read about which ladder you've been placed on.
http://www.laddertheory.com/
Last edited by Wakeup; 04-05-14 at 07:50 AM.
“The willingness to accept responsibility for one’s own life is the source from which self-respect springs.” ~Joan Didion