Flirting with a long-distance friend, bad idea?

Anonymous
I have a friend I'm extremely attracted to. In both a physical and non-physical way. We talk every day, whether via text, chat, skype, or phone. I confide a lot of things, personal things, to him, and feel like I can tell him anything.

We call each other "BFFs" and I rag on him for his girlfriend problems and he rags on me for my boyfriend problems. Admittedly, there is a mutual flirtation beneath the surface, and we've both said mildly suggestive things to each other at one point or another.

We remain "just friends" despite it. I have no plans moving to where he lives and he has no plans moving back here. So, there shouldn't be any reason why we should be too concerned with our feelings for one another. I also really like the person I'm currently dating, but he doesn't know anything about this friend of mine.

Is it wrong to continue our friendship in such a fashion? If I like him, should I tell him? Or would that just not be fair to either one of us? Flirting is harmless, right? The truth is, if he lived here, I think we'd probably be more than friends. What should I do?
Flirting with a long-distance friend, bad idea?
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