they're all messy teenagers. mako wasn't unique in making bad decisions.
are you just as mad at korra for kissing him without his consent? for korra coming into his workplace to yell at him and airbend his desk into a wall? an action lin beifong endorses because she tore up air temple island when teznin broke up with her. no one would laugh if mako did these things to either of them but they always seem to get a pass.
do you get mad about bolin kissing ginger without her consent? for both asami and bolin doing fuck all to help mako when he was framed by varrick?
bolin works for kuvira for three years but comes out the otherside because he did some good deeds but mako sacrifices himself to save republic city and he's still not good enough, he's not "redeemable" to fandom.
is it only mako that gets your ire because of the questionably written love triangle? he was indecisive and wishy-washy with korra and asami because he didn't want to hurt either of them which caused them all to get hurt anyway. he didn't do it because he had some master plan. he openly admits he messed up multiple times, both wu and tu call him out on it, and he apologizes to korra directly at the end of season 2 when they break up for real.
yet mako is the one that fandom holds to coals for over a decade about it. he grew and learned from his mistakes. korra and him literally have a whole ass bonding experience in season 4 that sorted their issues with each other from the previous season.
look people can have their opinions on mako. it's whatever. i'm not changing people's minds here but he's my favorite blorbo because i relate to him and fandom rips him to shreds. he's just some dude that fucked up at 18 with his interpersonal relationships. i'm glad my fuck ups at 18 aren't held against me just as badly.