I would never begrudge someone not liking a character, a ship, a chapter or even a plot arc, and I'll admit that I didn't fully expect the developments with Rin to happen on this timescale either. But I’m not convinced these developments are happening
too quickly.
Itsumi thought
Rin was pretty cute in chapter 7 and
almost went home with her then and there. She thought she could
see herself being with Rin in chapter 14 if Rin were nicer to her. She said she would
go on a date with Rin any time she was invited to in chapter 18. She was
happy to be treated like she belonged to Rin in chapter 20. In a lot of ways, the Rin scenes in this and the previous chapter were just confirmations of the
status quo established in chapter 25.
I'm not saying
other characters haven't had their
shippable moments with Itsumi, and more of that would be great. But Rin was introduced before either of the two other serious contenders, Yanagi and Kurohime, were; their interest in each other isn't a recent development. Itsumi
has definitely shown interest in other girls before and in between these developments. It would feel at least just as forced, if not more by now, were she to forget
Rin's many forceful advances whenever Rin's off-screen.
It'd be nice if Itsumi continued to get into sticky harem-y situations, not least of all because I think it could be really funny. I think it'd be fun if she and the Vice Prez were to kiss. It'd be nice to see Itsumi get her face caved in again, even if just with a dodgeball. And I'd love to see more consequences for Itsumi's previous liaisons. Mochi didn’t forget other girls like her; Kurohime's most recent advances came post-chapter 25.
I do think this series reads differently now from what it started out as, and although that's been the case since around chapter 14 or 16 (and although I personally have enjoyed the growth), I really don't begrudge anyone disliking the direction the plot has gone. By now it's been clear Mochi intend to write a continuous story in this setting and not just a string of unconnected gag chapters. Whatever their plan is, and whether it's good or bad, we'll find out soon enough.