Really good friends...
See this is why lesbians or bisexual women are treated so...invisible. Yes we are touchy feeling but do you realize that neither of them were super comfortable. Their was a tension between them, very little yes, but it was strongly there. Asami doesn't always act smitten. in fact shes very blunt.
During season 4 those two women had a shift within their relationship. by the end of season 3, Asami was very hesitant when she spoke to Korra after grabbing her hand.
I happen to come across an old post saying something about Asami snapping at Korra when they were discussing her father in episode 7. We all knew that was a very sensitive topic for her but the way she said. “You don’t get to disappear for three years and act like you know what’s best for me!”
That is a little giveaway of just how hurt Asami truly was for Korra's absents. That was not a friendly thing to say at all, that sounds like somebody angry at her lover.
Look its not about how you see things. This is what even Brian spoke about saying that if you look at it for a second time, knowing that Korra and Asami are together...those suitable subtexts or tbh main text by season 4 will make you see that there is something going one between Korra and Asami, even Mako could see their shift.
It was rushed I'll give it that, but honestly this was truly a very well executed way to show the growth of friendship to romantic.