She shows up at all of their games. Always sitting on the bleachers during training and watching Mako firebend, watching him move with ferocity – something that Korra has often been guilty of.
The Avatar is conflicted and confused. She doesn't want the other girl there, doesn't want Mako showing off to make her squeal and laugh with such ecstatic delight, but there's absolutely no way she can dislike Asami. She's too kind, too pretty, too feminine – too perfect, at least according to Mako.
Still, she resents the beautiful heiress… to an extent. Korra can't recall a time when a boy looked at her so thoughtfully, with such love; though she can remember every single time Mako has smiled at her.
Asami probably doesn't do that.
Mako grins at her too often for her to remember all of those precious moments.