Even for a guy who loves long hair, there can be a strong desire to cut it. Cutting or fantasizing about cutting brings out the delicate fleeting nature of long hair and the prospect of dramatic change. If he loves your long hair, he may have very conflicting feelings about these desires.

For a couple in a committed relationship where the guy loves her long hair, the guy cutting off the girl's long hair can be a powerful shared experience of bonding, control, sacrifice, and sexuality. She is giving up one of her best features and letting him take it, and he is giving up the pleasure of her long hair which he adores.

If a couple is not in a committed relationship, the guy may just be looking at her hair as trophy hunting, and like others said, be gone shortly after it is cut off.

If you want to cut your hair anyway, fine. If you are hesitant but see a future with this guy, maybe indulge him in talking/fantasizing about cutting your hair, but not actually doing it. Try to figure out what his specific desires are. If the interest develops into something mutually agreeable, then maybe you can set a future date for cutting off your hair. That gives him something to look forward to, the feeling of anticipation, and eventually the experience.

Not that you should at all bring up the marriage word early in a relationship, but letting your hair grow out for a long time and then letting him cut it short on your wedding night or honeymoon could be an amazing experience if he's into that sort of thing.