To a lot of fandom, platonic relationships and best friends aren't a thing. Every pair of characters who has any emotional interaction (including hatred) is shipped with each other. This applies to both straight and gay pairings.
There are fans who do this, the RWBY fandom being a good example. I do not do this, except as a joke. You can find plenty of sexually compatible platonic friendships in my & Alex's fiction. Platonic friendships and honorary siblings are great, and even more underrepresented than gays. So if it were that, I absolutely would not change it. But in this case we can take an educated guess at what the creator wanted it to be. And in this case, that ain't platonic.
To say nothing of the enormous amount of queer baiting various forms of media will do. Give us just enough that we get interested, then yank it all away.
Supernatural. One of the shows Alex is the very angriest at, for that "in love. ...with humanity" stunt. I thought it was hilarious, but I can see why other people got so pissed. That shit was mean shit.
(Frankly, I thought Mako got the short end of the stick, there. He wasn't nearly as unreasonable as people like to paint him, and he was jerked around a fair bit. Not saying he didn't make mistakes - the two-timing Korra and Asami deal was stupid, especially since it wasn't his intention - but he took a lot of abuse and then got vilified for it.)
Is he an incel? /s (Warning: Do not Google. Tumblr Bullshit.)
Mako is no more entitled to being given a girl as some kind of reward than any other human. And if you're going to go that direction, he was jerked around significantly less than Korra or Asami in the same time. They all took abuse. No-one vilified him except a vocal minority of the fans. Notice, he's still one of Korra's closest friends at the end of the series. In-universe, he's doing better off in life than Bolin.
