Not to be rude or offensive or anything, but Mais just not important enough to have her own revelation. It took Zuko about 2 1/2 seasons just to make the turnaround, and hes developed even further than what happened during Day of Black Sun. Mai, however, is a different story. She was only first mentionednever mind making an appearancein Book 2, and the only reason that she was a prominent character in Book 3 (alongside Ty Lee) was the fact that she was Zukos girlfriend.
Theres also the fact that the only reason she appeared on the show was because of the fact that she was trying to capture Zukothats right, she wanted to capture him! She was bored enough to do so, and the only time shes mentioned as having a crush on him before Book 3 (as a teenager) was in Return to Omashu, and the matter was never touched on again. Shes never really questioned right and wrongsimply going along with what Azula saysand shes really quite flippant about the war and doesnt really care about it or anything to do with it. Zuko, however, has always questioned right and wrong, and he does care about the war. Doesnt that indicate something about their romance being an epic FAIL?
Although, as I have already explained, Mai is not a bad person, simply an apathetic person. She is capable of doing good things, but only to save Zuko. I, too, remember The Boiling Rock, Part 2. But one good deed does not equal major turnaround revelation.