Why is it a problem? If her feelings for Sokka were substantial, then yeah, she got thrown under the bus. But there isn't any indication of that. She got that one throwaway joke and it was basically never brought up again. The next time romance for her comes up, she's clinging to Zuko. Plus her dialogue in Tales of Ba Sing Se implied that she was more concerned with the general idea of a romance and being attractive than anyone specific.
To me, this just characterized her as flirty, in her own tomboyish way. She had small crushes, but they weren't meaningful in any way, so they died pretty quick. I have no objection to that being used as a basis for a throwaway joke.