I'm sorry to say, but it sounds like he isn't interested in you, romantically anyway.
He enjoyed spending time with you as a friend, but that's it. Once you crossed the line, it sounds like he became a little freaked out.
I once worked with a guy who I got along with famously. We'd spend our breaks together, chat when either one of us wasn't busy, etc. He was who I considered my best guy friend. I'd confide in him when my boyfriend was being a jerk, and he'd be there to console me. Well, after almost two years of being completely clueless, I found out he had a HUGE crush on me. After that, things got weird. I began to question some of the things he did, and became worried that I was giving him a false sense of hope that we'd become "more than friends." To me, he was and always will be just a friend. I just didn't see him as a relationship prospect. Don't get me wrong - he was absolutely wonderful, but I just wasn't attracted to him
that way.
I would back off for a little while. Lay off the phone calls and text messages. Put your mind onto other things. Keep your prospects open - don't limit yourself to having a crush just on this guy. You'd be surprised how many other potential suitors there are when you stop focusing on one person and open yourself up to the big picture.
After awhile, (and I mean weeks, or even a month) try contacting him, but be
VERY casual and keep it to a minimum. Just something like, "Hey, it's been awhile. How have you been?" Really light and breezy. If he responds favourably, ease back into the friendship that way. If not, sorry honey, but you should do yourself a favour and move on. If not, it'll only torture you, and you deserve WAY better than that!