Yue is one of the many girls that Sokka managed to get in bed with. They had a nice relationship, but unfortunately Yue had to leave Sokka one day for important moon duties.
As a moon, she did a decent job, but wasn't re-elected for a second term. After leaving office, she decided to return back to her home to be subjugated to more sexism, but got lost in the North Pole. Despite being part polar bear or some shit, it was so cold she promptly grew balls, then froze them off. She got back home ok, but people are still looking for her balls. There's a ten thousand dollar reward for them, and you get to enslave someone of your choice.