I've been with two girls who know about my fetish.
My first GF back in like sophomore year of high school(Grade 10) had wavy black hair, about mid-back length. She let me play with her hair and pull it during sex and w/e, but she didn't know I had a full-on fetish until I got comfortable enough to tell her. When I did she completely ridiculed me. She called it creepy, unnatural, weird...you know. We broke up pretty soon after that. She said we were drifting apart but I'm 100% sure it was because of my fetish.
My second GF I met about a year after I graduated. Her hair was a couple inches past her hips, stick-straight, thick, golden blonde, and SOOO silky. She always let me brush it and play with it, and even put together that I had a hair fetish before I could even tell her. And she was more than accomodating! Hairjobs, hair pulling, hair smelling...anything to do with her hair, she was up for, although she'd only let me cum in it when she needed to wash it. One of my favorite things she'd do is wake me up in the mornings (when I stayed at her place or vice versa) by dragging her hair across my face and chest, and my cock if she was feeling extra frisky.
Unfortunately we broke up a little over a year ago. We're still friends and keep in touch quite often, but she's since cut her hair to about shoulder-length. I hope I can find another gem like her!
Also sorry for the long reply--I don't post here too often but I might start to. This was a pretty fun trip down memory lane!