There's a lot of subtext I'm missing here.
I feel like I didn't understand the chapter, so I'm gonna throw out what I feel like I got from it and somebody can correct me if I'm wrong:
Shuuji and Kaede were discussing whether or not Yuuki was suitable for being Takamine's boyfriend. Shuuji says that he could become Yuuki's rival (which either implies that he likes Takamine or he's just trying to get Yuuki to be aware that he could have rivals in the future depending on Takamine).
Kaede may or may not be developing feelings for Shuuji, but it seems clear that Shuuji does not reciprocate.
Kaede brings up that Shuuji has a "thing" with Shibuki, which I guess means that he may have feelings for Yuuki? Kaede definitely has a thing for Takamine though.
So, did I miss anything? Because that's a hell of a lot to dump all at once and the conversation was left pretty vague.