I try not to read anti-Zutara takes because like, help, I'm literally here to escape the dark divisive real world. But one point that I see over and over is that there's no time between when Katara forgives Zuko and the end of the series for the dynamic to shift between them.
I always found this kind of a surprising argument (leaving aside all the narrative and thematic groundwork already laid between these two characters, and also the in-show precedent for compressed romantic timelines like Sokka and Yue) because of the Ember Island of it all.
Between the scene where Katara forgives Zuko and the scene when he jumps in front of lightning to save her (both romance-coded visuals), they're living for weeks as unsupervised teenagers in beautiful beach house, emotions running higher than ever as they face down the end of the world as they know it, in a location the story has already told us "has a special way of smoothing even the most ragged edges."
It's kind of hard to imagine a setting or situation with more romantic potential. Except maybe the moment after Katara saves Zuko after he risked his life to save her.
I'm not saying the show cashed in on that potential, obviously. I just mean that one scene with the two of them having a heart-to-heart on the beach late at night or flirting in the surf would have been pretty much all it took.
