Maybe my take on things is different and I'm being too generous with events, but I think what is being shown is that people can't run from their feelings.
Yami tried to run from her feelings for Yuu and bury them. She failed.
She tried to give Yuu his happy ending in a shitty way to get him to move on. She failed.
Yami tried not to hurt Hikari once she realized who Hikari was in love with. Yami is currently failing.
She knows she isn't a good person(in her mind) and she doesn't deserve Yuu. Her heart says otherwise.
The only way all of this could've been avoided and Yuu/Hikari get their happy ending is if she had transferred schools and never met Hikari.
That would be a boring story
Oof, it hits me that in each of those examples you list (and your take on them,) that it's:
- Yami trying to do what she thinks is an overall good thing...
- ...by sacrificing what she thought would only be herself.
Also, with this chapter, add to that list: "Yami is trying to push Yuu and Hikari together by reassuring Hikari that Yuu loves her back.
She may be wrong."
I think the most tragic thing about the pre-rugpull and more "present-day" post-rugpull chapters is that they show us that Yami actually
was kind of successful in running from her feelings for Yuu to focus on the family she nuked to protect herself from her stepdad. Like, we see that Ayami is in a much better place where she can be Hikari's actual BFF and not just some project that Hikari's trying to save.
And all of that would have gone fine if he didn't accidentally find her again.
I'm not sure Yuu & Hikari's happy ending as a couple could be guaranteed unless Ayami and Yuu never met, though - it may have already been too late for them by the time Yuu fell for Yami, if he realized "Oh, THIS is love, and what I'd felt for Hikari all along was a childish crush/admiration."