Wait, is Kuro much more self aware than I thought? She always acted as if she never had any feelings and was just a really good friend (or felt like she could never compare), but I suppose that was the idea.
I think the implication in the previous chapter (chapter 25)––when Kuro's otaku friends fill Iroha in on the previous relationship of Kuro and Fijishiro––is that Kurokawa has been suppressing an attraction to Fujishiro since long before she and Fujishiro became friends. We get those panels where the otaku Kurokawa of old stares unself-consiously at Fujishiro as she hangs out with the other gyarus, and we're told that Kurokawa's friends found it "scary," like they couldn't fathom Kurokawa's fixation (interestingly, it seems like Izumi is looking bemused towards Kurokawa in this flashback, while Miki and Fujishiro and the other one are oblivious to Kurokawa's stare––I wonder if that's intimating a story element yet to be explored?). And I imagine Kurokawa has rationalized her intense preoccupation to herself all along by convincing herself she's a "Fujishiro–stan." She has probably felt that her feelings towards Fujishiro couldn't be love because she and Fujishiro weren't, in her eyes, social equals. But it starts to suggest that Kurokawa showing up for Fujishiro's breakup with her boyfriend might be less of a coincidence than it seemed at first. Perhaps Kurokawa subconsciously elected to become a voyeur at that moment––she could have scurried away when she saw Fujishiro and her boyfriend coming. The panels showing Kurokawa staring at Fujishiro in chapter 25 maker Kurokawa look as if she's in a trance.
Every chapter that ends with Fujishiro looking like her feelings just got smushed and not understanding why is making my heart hurt, but hopefully an explosion of jealousy is going to erupt from her in subsequent chapters. I like what's been done with the story so far, but I do feel like the volatile Fujishiro of the early chapters––the one that was ready to blow up her own life every time she flew off the handle at someone––has mellowed out a lot over the course of the series. Reading the backmatter in the 2nd collection, the author mentions that the series was only supposed to run for two volumes initially––and it does seem at around that point that Fujishiro starts to back off a little and sublimate some of her edge (if you want your series to stretch out longer, the character can't be quite so aggressive all the time, I suppose). After that second volume the supporting characters start to take on a lot more life, and in there you have the Izumi arc that pretty much hijacks what was the main drama of the series up until that point. That move was surprising and the arc turned out to be really moving, but I think it ended up introducing a level of emotional intensity to the series that I imagine the main romance––which was heretofore a lot frothier––might struggle to match. So I think it would be good to see that impulsive, emotive side of Fujishiro re-emerge, especially when dealing with her own feelings––ones that she clearly doesn't yet understand. A slightly darker Kurokawa is probably a good move towards making the ultimate romantic conflict between them more intense. If Kurokawa is a little more intractable in her belief that Fujishiro is on a level Kurokawa can't touch, it's going to make it harder for Fujishiro to eventually press her case and assert her own feelings––once she figures those feelings out.