It's over

I suppose that this should come as no surprise. After a week of getting feedback from everyone but him, I've concluded that it's over. Why? I've called him on two or three occasions this week and he hasn't bothered to call me back. In addition to that, he used to call me every night now he never calls me! There has been no talk of whether or not he's seeing the person that he was
"casually dating" when he first began to see me, but I can only conclude that he's still doing so. I don't need to be stressing over someone that I've known for so little time. If he's not on the same page as me, (which based on my lack of certainty on the matter proves that he is not), it is not worth it to continue to waste my time and energies. I'd rather not get embittered and wind up hating him, nor do I want to continue with things as they are and continue to like him even more. I'm really starting to feel down now because I really liked this guy! I guess that I should just leave guys alone for a while. Not calling him will be the hardest...any suggestions?