Welcome! Your boyfriend is extremely lucky to have someone as open-minded as you .

As far as reciprocating his passion is concerned, I think the best thing to do is to ask him what he wants to do with your hair (if you haven't already) because the answers you get here won't mean much unless they match with his preferences.

For me personally,what truly excites me about a woman's hair is the way it moves when she shakes her head, especially if it is thick and long.

Lucky for me, my girlfriend has thick,straight,sweet-smelling hair that reaches her waist.

When she shakes her head, the smell of her shampoo is released into the room and i get instantly aroused, even more so if I position my penis directly under her shaking hair.

But that's just me. Hair fetishes can vary based on length, style, texture, actions performed with the hair (e.g. hairjobs, cumming in hair), and more.