Girls, I'm having a hard time with this breakup. Advice?

I've been in long, serious relationships before (one year and three years) and when they ended I was upset, angry, etc. How I felt during those breakups feels nothing like how I feel with the one I just went through a couple days ago. We had only been dating for about four months but it was completely different than my past relationships. We completed each other, a perfect compliment for the other. Then, he dropped the bomb on me (after acting normal ALL day) and told me he wanted to see other people. He said the spark had faded (well yeah, we moved out of the happy happy beginning of a relationship and moved into the comfortable stage), but he had never even gotten to this point with a girl in the past. He's never been in a relationship for over two months before me and he's used to being the single guy who can sleep with anyone he wants. I think he's afraid of getting too serious and being tied down.
I don't know what to do! I can't quit crying, can't eat, can't sleep. It's killing me. TwoX, can you guys talk me through this?

If it matters, I'm 23, he's 24. Also, if things don't work out with him in the end (though I wish they would...) where do I meet decent men? I'm sick of meeting guys online and I really don't go out to bars or anything.

Edit: Thanks girls for the words of wisdom, they definitely made me feel a little better. I fell asleep before reading most of the comments last night but I read them all now and I'm so thankful for a great community like you guys. XOXO.