Okay, i don't want to come across as harsh or anything, and it shouldnt be taken this way, but here is how i see your situation. This guy obviously was head over heals for you originally, and u kept him at friends length at first. Up to there you played it fine, but once you started waiting/doing more without wanting a monogamous relationship you were leading him on. Thats where you went wrong, knowing that wasn't what he wanted. Its hard with hormones flying and everything, i can relate.. you make decisions that arn't best for your friendship.
So pretty much, u lead this guy on and then told him it wasn't going to happen, so he was probably lot more crushed then you think. I know i would be. Now, where you stand now: Before i even read your second post, i knew he still had feelings for you. After you spend so much time trying get a girl like he did, you don't just forget her overnight. And you are not a rebound for some other girl. Quite the opposite, he was trying to see someone else in order to get over you, but it obviously didn't work out.
Now he's left there no sure if he should put himself out there for you, because he has doubts about putting his feelings on the line again, as he did the first time just to get hurt again. He still has feelings, hes just confused about what to do. Which is why you two are still close, because he still feels it.
I agree with others it's not in your best interest (or his) to keep sleeping together, but give him some time and see where things go. Maybe he needs a little more time to see how things are between the two of you. He's probably afraid you will change your opinion on relationships again really quickly.
Just a thought from someone who has been in a couple situations w friends involved =