I’m so happy she told him that Sousuke called at the start ! They usually keep this quiet in mangas because they don’t want to worry the BF but that just makes the situation worse when they do that
So it was her karma that let Hijiri and Koyori hook up in the first place. I mean, if the sly girl hadn’t lied about a child and made Koyori break up with her ex-boyfriend, Koyori would not have had that first night with Hijiri. She totally did this to herself.
And her smiling face is really creepy. The author did a really good job of drawing a fake smile.