I didn't see it b/c I was watching the Grammys, but I figured from the previews last week that this was what would happen.
I think it wouldn't be so weird if they had developed the relationship with the Russian a little more quickly. It still feels very new and "walking on eggshells" for her to up and move to Paris. We all say he's not caring enough or whatever, but that's how Big was too. The only lovey-dovey relationship she's ever had was with Aiden. And she srewed that up royaly. I don't think she's cut out for the "perfect" guy, so maybe the Russian will be good for her in the long run - always a bit of a challenge, but obviously into her (unlike Big who wouldn't commit to her but was willing to marry someone else!).
Of course, maybe they will surprise us and she'll go to Paris, hate it, and move back to NY and live with Miranda and Steve in Brooklyn!