Why are we still just friends?

So a guy and I have everything in common, so much so you would think we were twins (but diff enough to not bore each other). We talk most every day for hours (and I mean HOURS) on IM, text whatever medium there is. In fact we have not missed a day in 7 months. Even when we weren't getting along we talked. He has told me is physically attracted to me and we get along very well, even when we don't we do if that makes sense.

However, we do work together, so at different points we both decided we best not get involved. However, the more time we spend the more it seems that reason is not really valid enough.

So now, he is dating a few women, one he even says is a bit serious though can only be so much because he is still dating several and it has not been for very long. The thing is he still seems to like me...even jokes about it, but then when push comes to shove he won't go forward with it even though he knows now I am OK with ignoring the work issue.

NOTE he says I am one of the people he is closest to in his life and he has told me he loves me (as a friend of course)

So guess is - does anyone have any insight into this.. and also How is it you can spend so much time talking to someone.. many days from morning til bed, have everything in common, get along so well, be sexually attracted to the point where he sometimes has not spent physical time w me because he was afraid we would sleep together and never do anything about it? Also it often feels like I am a relationship, not just friendship.

And because we seem to have everything you could need to make a relationship work it is hard to watch him date others, so tips on dealing with that would be great too.

(PS we are in our early thirties)