it’s established pretty early on that Kenta has always been a bit weird regarding Kiyo (chapter 20 or so, his second or third appearance). In comparison, despite having numerous interactions with him at that point, Suu’s crush on Kenta is not so much as even implied at until nearly 100 chapters in, when it is very suddenly shoehorned in, and not even as a recent development, but as something that has apparently been going on since they were small children.
And then it becomes a major focus in the recent chapters, taking away from pretty much everything else, especially Kiyo, who feels more like a sudden obstacle/stage prop in the relationship dynamic.