Thanks for the translation!
The dialogue got kind of hard to follow during Miya and Itone's conversation. But the upshot I got from it is, Itone was slipping into yandere-dom not just because Harutaka broke up with her, but because she was slowly getting isolated from everyone. We'd already seen how her other friends were distancing themselves from her after her "deliberately not invite Miya to the study group" stunt, and she was never more than allies of convenience with Yura. Her obsession with Harutaka may have been the result of her feeling like nobody else would ever care about her. That's why Miya making a sincere effort to repair their friendship moved her enough to bring her back from the brink.
What's ironic is that as Miya, Yura, and even Itone are slowly becoming better people, Harutaka is just getting worse; in this chapter he is openly hitting on his "best friend's" girlfriend, which frankly is worse than anything any other character has done in this manga. It legit baffles me that nobody called him out on it. This kid needs a serious intervention.