The way I see it is that the only way that Chiyo reconsider is if she hears the truth of what happened that night from someone else, possibly Kitamoto, though he's unlikely to tell her as he would like to be next in line to be her boyfriend.
The one thing I do fear is that Chiyo will hook up with and start dating Ookuma. If that were to actually happen, I would probably stop reading this and wait until it was all over and then finish reading it. And maybe not even then.
There was one comment in the comment section for this chapter on comicojp that I found interesting:
傷ついたというより、五十嵐を軽蔑してるだけのように思える。
It seems like you're just despising Igarashi rather than being hurt.
which certainly seems like how Chiyo is reacting.
It brings me back to a fear that I have had for a long time about her if they were to break up, that Chiyo would act rashly and do something very spiteful just to "get even" with Igarashi, like spending the night in a Love Hotel with someone having sex (Ookuma comes to mind) and send photos to Igarashi. The thought that Chiyo might have sex with Ookuma as revenge upon Igarashi first occured to me a very, very long time ago while charlemagne was still translating the series. However, the idea of Igarashi getting shit-faced and ending up spending the night in a Love Hotel with Subaru never crossed my mind, but Coco made it happen. If she's willing to do that, it's not much of a stretch to have Chiyo spend the night in a Love Hotel with Ookuma, though it would probably be Ookuma, not Chiyo, who sends pictures to Igarashi of them having sex.
I cannot wholeheartedly feel good about Subaru. Although her heart might be in the right place, her actions are those of a scheming bitch. She knows the Igarashi has a girlfriend, but she intentionally attempts to get him to betray his girlfriend in the worst possible ways. She might be the best girlfriend for Igarashi once she gets there, but she is using very underhanded tactics that I can't approve of. What should have happened after Igarashi got shit-faced is that one of his senpai should have taken Igarashi home.