Makorra was only “endgame” as far as the end of Book 1. Once we got into Book 2 we knew we were going to have them break up, and we never planned on getting them back together. Sorry, friends. I like Mako too, and I am sure he will be just fine in the romance department. He grew up and learned about himself through his relationships with Asami and Korra, and he’s a better person for it, and he’ll be a better partner for whomever he ends up with.