Seriously, I only talk about my hair fetish with my couples. NEVER with a friend. 'Cause if a friend now about my fetish for sure it will be annoyed.
If you have opportunities of being romantically or sexually with your friend you can tell her about it, but after you gain her love, never before, or never if it's only your friend.
You can do wathever you want my friend, but if you tell about this it's almost sure she will block of her life.