How can i miss him so much?

It's weird. I've never felt this way before. I think about him EVERY DAY and yet I know that I'll NEVER see him again. How can this be? Logically my mind should dismiss the notion of us ever being together again, of me kissing him or holding him, but it doesn't. And I find myself daydreaming of what I would do with him if he were here, or I'll visit old memories of when we were together for that short time. You would think that I loved him, but I don't think I did. I simply loved life while I was with him, because all my problems weren't staring me in the face, he was. Whether it was or not it was still something stronger than I have ever known.
If I eliminate all emotion and put it as plainly as I can then I would have to say it was simply the sex. Certain chemicals are released during and after sex to tie a couple together, this ensures that the offspring has a better chance at survival. unfortunately for me it would seem that those chemicals skipped him and all went into me. And so here I am suffering while he's free, free of emotions, free of commitment, and above all free of me.
Perhaps I will look back at this in a month or even a year and realize I was overreacting, he didn't like me and so he moved on. But looking back at all my past experiences, they all changed me and that in itself is something to over react upon. I lost my virginity to him, i opened up to him and i got painfully crushed and rejected by him. No matter how much time goes by he is implanted into my being and has changed who I am. I can't ever forget him and perhaps Thats why i can't simply stick with logic and realized I was being used and am better off alone. Because right now nothing can be farther from the truth. I am so lonely and sad and I want him and only him. I imagine us together, I fantasize of his touch, and still even though I know 100% that he will never call or text me again I prey for his call. 
It boggles my mind that I know he is lost from me forever and yet he is so close to my mind, in fact he never truly leaves it. What am I to do? Answer: nothing, just live like I have been. Wake up each morning breath in and out all day, try to think of different things and at the end of the day hold back the tears so that I can have enough strength to try it again tomorrow without him by my side.
Is this normal to feel this way about a guy I was with for only a month and a half and who was only after one thing, sex?