The previews have been hinting that Aang might have to choose between his feelings for Katara and mastering the Avatar State. That...makes me sad. I don't ship Aang/Katara, but Aang's crush on her is adorable, and he's serious about his feelings. He very nearly confessed in the last episode, and now the Guru is going to tell him to let her go? That's so sad. T__T
Of course, it might be that the previews are misleading us, like they might be misleading us with the first Zuko+Katara preview. But still, it seems like it's going to be an emotional couple of episodes for Aang, Katara, and Zuko. Even the episode title "The Crossroads of Destiny" sounds very epic. The previews are making me more excited for it, and at the same time, apprehensive for the changes to come.