Again, this goes into some very abstract, conceptual stuff. But the gist of it, as I understood it, it deals with love as attachment. The purpose of the avatar is to be connected not to just any one person, but the entire world. The avatar must strive to love every person on earth. His love for Katara remained, but it's not a love that's bound by earthly attachment. It relates to the previous Air Chakra. Aang loved and was loved by Monk Gyatso. He died, but his love remained, and was transferred to Katara. So, he's basically saying he's let go of the attachment he has to Katara, but not the love, which can go be transferred to anyone else. So basically he loves her, but he's not in love with being in love with her and he's able to project that love on others.
Fair enough. I think we can end it here, since all we disagree on are technicalities. It's one of the most peaceful debates I've had over this, really.
Pretty much like you just said, it doesn't excuse it. There are plenty of ways they could have done it, even if they were to end it on the cliffhanger. I would not have been upset about the series ending with Korra finally humbly learning that she needs to buck down and really learn spirituality as it is meant to be.
