It looks like Coco is just going to keep Igarashi in the dark, as well as continuing to characterize him as a clueless buffoon. If he doesn't confront Chiyo about what he overheard the next time they are alone, he'll become a spineless buffoon.
Coco is also forging ahead with the plan to make Ookuma a likeable and sympathetic character, as well as make him even more likeable than Igarashi. It's not working with me, though it does seem to be working with Chiyo. I fear that, if Coco pushes this too far, not only will Chiyo and Ookuma end up together, but Chiyo will also become one of my most detested heroines.
It also really grated on my nerves that Chiyo could spend enough time with Ookuma in the middle of the night to have a hot beverage, but she could only spend two seconds with her "boyfriend," let alone lying to him. If you can't sleep, why not spend some time with your "boyfriend?"
That fake, Miss Goody Twoshoes "good morning" smile also pissed me off.