Ok, I just read through the older comments, and I think there might be a different way to interpret the back cover. I don't have any evidence to back this up, it's just on speculation, but I'll put it in spoiler tags anyways:
What if, at the end, the big argument is resolved by Kotooka apologizing and explaining her past to Tsukasa and Washio, where they discover Kotooka's feelings on homosexuality. Tsukasa then confesses to Washio and Washio, knowing that Kotooka is against homosexualty, decides to date Tsukasa. Kotooka notices Tsukasa acts differently and she, knowing that Kotooka wouldn't be comfortable with her and Washio's relationship, tells her that she got a boyfriend. The boyfriend in question is actually Washio. Tsukasa and Washio grow closer, while Kotooka grows more distant, partly due to their falling out and partly due to them growing up. They still get together as the old trio from time to time. Washio brings up the wedding as a very nonchalant remark for a conversation topic to make it seem like she only heard of it through word of mouth in front of Kotooka, even though she likely knew a lot of the details already from Tsukasa herself. It would also kind of explain why Tsukasa becomes so flustered when Kotooka brings the subject up.
Well, it's a bit convoluted as it is right now, but I think it still makes more sense than what everyone else is thinking with the way the manga had been going so far. Still, anything could happen I guess.
I would like that end. Hope so then we should see. . I skipped the part with the history of him this chapter. Don't like him either way
