Well I feel she should do more for the fetish than just lay her hair on your stomach. Tell her that if she wants to REALLY get you off, she will stroke you sensually with her hair on your penis or whatever you would enjoy. You want to make it seem as if you're giving her the key to your door, so to speak. I mean something like this she should really take advantage of. You already made progress by opening up about this. Now you gotta push things a little further now and tell her how much you enjoy her hair, how you enjoy how it feels, smells, etc. and how you'll benefit greatly if she uses it on you. You gotta start opening up to the fantasies that you want to have done to you. Now if it ends up that she doesn't want you to jizz on her hair or whatever, at least you gave it a shot. What you could also do if that point occurs is to see if you can come up with a compromise or an alternative.