I'm sorry he seemed to just "fade away" metalchick. I'd feel hurt by that too. And how disappointing. How long ago was your last interaction? If it was recent, you could ask what happened. To get closure. Though, there's no telling what his reason may be. And his reason may hurt, too.

I have heard stories like this before about dating, so you're not alone in having someone express interest, only to suddenly change. It happens in the dating world, it appears. I'm sorry you had this experience, though.