Okay, from your latest posts I would say you are in with a chance after all. You should still probe her for more information about her boyfriend to be sure. As a long distance relationship the chances are that it's not going to work out, but you do still want to know where things stand.
Also, forget about previous advice to just tell her how you feel. In my case I gave that advice on the basis that she's probably not interested romantically so you might as well get the pain over with. Sizzling Berry is right, attraction is complicated and tends to work "in the moment". Next time another moment like the ones you describe arises, just seize it. Throw away your inhibitions and make a pass at her. I know that's easier said than done, but it's how it works.