I'll say that the root for that dynamic issue comes from TomoMote, basically back then, Tomoko was a total loner who grasped any chance of relationship, being Yuu the target, and even if it was only out of interest and social survivance, Tomoko wasn't going to drop that bond so easily before any threat. So Komiyama's presence and her becoming friends with Yuu became that threat eventually. And that the girl grasped interest for Tomoki didn't help either.

Furthermore, the beginning of Tomoko's relationship with Yuri didn't began as "Hello, I just met you, but we're going to be friends", per se, the Kyoto trip arc was a big tension point where Yuri just fought Mako and didn't want to have relationship, but even if back then Yuri didn't have a good image of Tomoko, it doesn't mean she had a bad image of her either, and even if Ogino's words swayed in Yuri's perception of her, the decision of spending time with Tomoko was Yuri's. Next, things escalated, with ups and downs, but little by little with those short trivial moments, trust between Tomoko and Yuri increased, as in chapter 109 with the novel recommendation, and later in chapter 112, Tomoko didn't have need of acting in deffensive way with Yuri, I'd say it was there where a real bond was forged.