except people don't just magically improve or get better because you help them or you force them to.
Koto is literally trapped in a circle of depressive thoughts/feeling worthless, and it's very hard to get out of that, EVEN WITH PROFESSIONAL HELP. Mariya needed to realize that sometimes despite her best effort and all the good intentions in the world, she won't be able to help someone.
Also, imo, Mariya isn't a burden but her help is not good for Koto at all. Koto forces herself into a mold of someone that Mariya wants, she basically operates on the fear of disappointing Mariya, and that is honestly a terrible and self-destructive way to live.
What Koto needs is god damn therapy, she's depressed as fck and no amount of "friendship magic" will fix that.
^ so much this
Ultimately, as others have mentioned, Shiki's current angle of "oh she's just like this" is toxic too (or at least that's how I interpreted her recent takes), but that doesn't justify Mariya's methods. This is why you need a professional for this kinda stuff
Really happy to see some sincere development on Mariya's part, I hope they can go back to getting along (but it's gonna take a lot of work, like everything else in Koto's life lol...)
Also happy to see the tag changes! I think the new ones reflect the series' workings a lot better