You're actually the first person I've heard saying they're addicted to SF4. For what it's worth, I do the same thing too. I have yet to finish games like Skyrim, Dark Souls, Deus Ex:HR, and a few others just because I keep going back to SF4. I'm playing persona 4 right now but I have a feeling I'll fall back to SF4.
It's not really a problem for me because I'll eventually go back to those games and make some progress (no matter how little). The only situation I see myself stop playing any game is if it has been detrimental to my life rather than other games.
I mean, the big tent pole titles like the latest Assassin's Creed, Portal 2, Arkham City and the like would hold my attention till I finished, but not much else. Right back to it. And for some reason, only 4. MvC3 couldn't keep me interested, KoFs, SFxT...none of them beyond SF4 and it's iterations.
Nothing I couldn't back off of in terms of real life shit, but man, it had a stranglehold on other games for the most part.
You're done with fighting games right when TTT2 is about to come out? How sad.
It would be if I ever had any interest in Tekken.