Hi, from what I understand you don't want the girl to think that to you she is just a long hair. Try to really convey to her that you respect her and appreciate her human qualities. Let her know the sexual aspect of your relationships as just another "layer", which is not the major, but still very important, cuz it is, especially while you're young.

During sex demonstrate to her how much it turns you on. Maybe while you're out show how proud you are that she has long hair and that it really makes her stand out. Point out how man (and especially women, who can be either jealous or even turned on) are paying attention to her hair. Don't forget to complement her on other parts of her physique! And always, always remember to show your sincere appreciation for her human qualities. Take care of her and if she's smart she will want to pay it back with pleasing you. Growing her hair longer is such a small favor really! And if she doesn't realize that after all your efforts or is reluctant to make steps towards your sexual needs, well, maybe you should think twice if she's worth it.

And just one more advice: don't think of your long hair attraction as a "kink" or a "fetish". It's as natural as feeling of hunger or thirst. Long healthy hair speaks to our genetic programming. It says "That's a healthy mate".