Oh, well. I've been where you are, (((Pirouette))). If he has it in his mind not to get involved, there's no pheromone on the planet that'll change that.
Not knowing his background it could be anything from a broken heart to ?. He has his reasons whatever they are. It's OK and understandable even though we may not like it.
If you haven't seen him canoodling to any degree with someone else, then he probably really isn't interested in a serious relationship with anyone. Not right now, anyways. Still, you'll have the opportunity to be around him because you have common interests and you can continue to engage him on whatever level he's comfortable with and just get to know him the best he'll let you. If/when he ever wants more he'll let you know.
In the meantime, there are other attractive fish to be snagged! Seriously, you
are way too fabulous to hover on the sidelines waiting for this guy to wake up.
Nothing against him, I'm sure he's a perfectly nice guy, especially if he's peaked your interest. But it's time to rebait your hook and start fishing in a different pond. I'm not telling you to go after Moby Dick, lol. Sometimes it takes the interest of another for someone to see that the tasty morsel is being nibbled by someone else. And you never know, if you concentrate on fishing elsewhere for awhile he might begin to miss you.
Personally, I'm up for a good chase to a point. I've done the unrequited love thing and it sucks. No matter how attractive I find him, after awhile if he's no respondo it gets tiresome and, sadly, it's time to move on.