What is this guy thinking and why did he suddenly change his behavior?

I was friends with this guy for a few months. We met online. He works a LOT so we never got around to hanging out until...

At the end of last year, he started pursuing me like crazy, we hit it off, hung out and talked a lot. He did lots of sweet things for me, kept telling me why he liked me, and got shy when I smiled at him.

One month later, we both got crazy busy and it was hard to see each other. We hung out once, he asked when I was free again, but I turned the question back at him since he's busier than me. He said he'd let me know the next day to make plans for the weekend.

He sent an email saying he still hasn't figured out his schedule but would find out real soon. But days passed and I didn't get a response from him.

So I waited 3 days and finally sent him a text asking if he was ok. He just said that he was working 16 hour days. Then I asked him about weekend plans and he didn't respond. I wait out the weekend not texting or emailing.

Finally I sent him an email laying out details of what happened: we hung out a lot, got busy, then nothing, but I said I still liked him, and told him to call me. It was a long email, but mostly laying out facts.

A few hours later, he told me that he was sorry for not getting back to me, and that he doesn't know what's wrong with him, and that he was working all weekend, and that he'd reply to my email.

Nope, he never replied to my email. I texted him once to ask what he was doing that night, then IM'd him an hour later with one short message saying 'what's up', and then stopped. He didn't respond to my email like he said, he didn't respond to my text, or to my IM. I stopped trying. It's been a good 4 weeks since we last talked.

I still think about him a lot, and am obviously still disappointed.

He was so direct about everything from the get-go. My email was pretty straightforward, so I figured he'd at least tell me 'i'm not interested anymore'. But I didn't even get that.

More info: I should also add that we met on an online dating/social networking site. Neither of us really meet people off of it, we just killed a bit of time using it. After a month of dating, we both deactivated our accounts. A few days after he ignored(?) me, I reactivated my account and saw that he wasn't back on it. But he reactivated a few days later...and viewed my profile several times. Yet he did not contact me.

What the heck is going on?

What is this guy thinking and why did he suddenly change his behavior?
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