It's probably like people said, he was tryin hard, and doesn't really know if you want unlimited attention or not. Whenever I get the slightest vibe from a girl that I'm kinda pushing personal space, I back waaay off and give them too much, hence they kinda distance from me. I would try implying you might want more attention, or get in his personal space. If he gives get away from me vibes, then I can't help you at that point. I have no idea why he would want to do that.
Actually...
If he really is trying to get more personal space for himself, there could be a few reasons.
If your ever distracting him from his work or hobbies that require focus, that could easily piss him off. Don't ever ever break our concentration for something silly. We don't mind silly otherwise, but that's the one time, you DO NOT want to break concentration. Either he'll contain his agony, or he'll snap at you like I would. If your helping him, that's a totally different story.
It's not like he loves his hobbies more than you. He might, I have no idea, but telling us to give equal attention to a person, and a hobby at the same time is like asking an elephant to juggle 20 peanuts.
That MIGHT be the case.
Otherwise I would say that he just thinks he would be invading your personal space if he does give you attention. First try implying he can give you plenty of attention. Or, you could get a little blatant. You could say something like;
"Bob, I don't mean to sound like a clingy girlfriend, but you don't (x) much anymore. Why is that?"
x = Whatever thing he did to give you attention.
You can mix, match, and meld that statement to fit your social behaviors towards each other, or you could use it as is, but I think you get the idea.