I just dislike him for what he did to Asami. She’s been a excellent girlfriend, Helped made his dreams come true, took care of him and his brother for (albeit a short) a time. Yet he regardless gravitated towards Korra, especially in a very turbulent time in Asami’s life. She lost her wealth, her home, and her father. I don’t know any sane woman who would have looked him in the face and said “It’s okay, leave and and go be with her.” even thought she’s been pretty much perfect.
Yes, he’s following his heart, but it was a huge “fuck you” to a good woman who did nothing wrong. It doesn’t really matter what angle you observe it from, it was messed up.
I dislike him for what he’s done, not who he is. His character is well developed, and he’s a good guy. I really wish he didn’t burn Asami like that though.