the kanamari arc makes sense. just saying. i just think people tend to forget how being a fifteen year old makes you feel.
so kanan met mari when they were kids. kanan must have noticed the difference between them back then: mari had tons of money and she did not. but she probably didn’t care when she was still a kid and money and actual responsabilities and their futures were things that didn’t matter.
mari was offered the abroad thing and i bet that when kanan knew it, she thought this: i won’t ever leave this town. dia will also stay. mari is the only one that has a chance. she needs to take it and be shiny. so she decided that she would do ANYTHING and EVERYTHING for mari to leave the town and be succesful. she had to take the chances she was given (and maybe she was also lowkey jealous).
mari comes back. kanan treats her like that because she’s mad because mari is wasting her chance (a chance kanan could only dream of) and because she isn’t being thankful. kanan wonders why the heck mari is back at the town wasting a chance so many people would instantly take. maybe she also thinks she’s acting spoiled (and that doesn’t help her feel better).
mari slaps her. she waits for kanan to slap her as well. kanan wants to, but then she actually sees everything (mari, one of her best friends ever is waiting for her to slap her) and hugs her like when they were kids because there are some friendship things we won’t ever be able to explain but aren’t less credible or occurring.
no one is abusive. no one is a bad person. they’re just teens. and most of teens like to do what they want: mari wanted to stay and kanan wanted mari to be succesful and happy and didn’t realize mari was happy there. again: people tend to forget how being a teen feels, and how much one can love a friend.