I'm quite satisfied with the ending tbh, not only that the author gave a reason why Yuna is the one, but also we got some bit of a story how would it be if Kogarashi ends up with the other girls as well
The only, well, downside on this manga is that nonko, urara, chitose, yaya, rui, Chisaki's mom, todoroki, shiratsuyu, and SAKURA is not included in the harem list! And the interaction with Sakura, who seems to be important, is forgotten just like that, I mean come on now, really author? The boy works his ass off for her and you barely gave us interaction between the two