Really don't think one could call these relationships "deeper and more complex than the majority of series"- that just is disingenuous and factually wrong. Kanoko inherently is a pretty shallow character, her whole existence is angst because of lesbian feelings for hime.. That is it. She did not develop or grow or deepen. There was nothing more to her. We just now went full circle these past chapters with two slight additions; she is a bit more confident and absolutely annoying in being that repetitive. Sumika on the other hand is a splendid character that could be described as complex and deep, I guess.
Also, that is a whole arc pretty much wasted. I learned nothing apart from: holy shit is Kanoko one annoying and infinitely selfish piece of s! That alone makes this just not deeper and more complex than MANY (majority..) other great series out there- it most certainly can not be masterful with a whole arc wasted...
I mean, the arc wasn't wasted cause it resolve Sumika and Nene's arc. On it way to resolve Sumika and Kanoko's relationship, Sumika growth as a character, same with giving Nene's story a closure.
The reason, I'm spitballing here, why the author won't let her confessed because we already see Hime's reaction to Yano confessing to her, so if they do it, it gonna be a repeat of the ending of that (with even a bigger shock for Hime because she believe that Kanoko never hide anything from her), and the triangle relationship between Hime/Yano/Kanoko, which I'm sure is the end game of this manga so that gonna be it own storyline after we resolve the relationship of Sumika and Kanoko.
They go slow i think because they don't want it to get too messy, imagine a storyline where they have to juggle the triagle relationship + Sumika's feeling for Kanoko + Nene watching the whole thing happen, that would be an even bigger mess.
Like, I understand people have their ship that they want to see progress, but I like that the author still working on cleaning up all the plot thread and storyline they lay out. People can hate a character and it's fine, but Yano whole existence is also angst because lesbian feelings for Hime, and she been holding to that angst even longer than Kanoko. and Kanoko was teached to be this selfish by Hime, the most selfish character of this whole series (regarding relationship) so you can't even put that on Kanoko.