I have found long hair very exciting ever since I was a young boy. It's something that I have never gotten over and it has now become a primary source of sexual stimulation. In fact, it became the primary reason of my pending divorce (she couldn't understand it).
I too have had hair-cutting fantasies but I also know that the short-lived excitement that would be derived from it would not be worth the long-term excitement that comes from being with a beautiful woman with a long mane.
For me, it became something that I would only talk about but never could act upon. Hopefully, his cutting fantasy is something that he can overcome. If I were you, I would try to explore whether this is something that we would want to act upon or merely likes to talk about.
We all deserve the opportunity to find a special long-haired woman that understands us and accepts us for we are. You sound like one of these special women and I wish you the best of luck.