Under risk of some people wanting to skin me alive, I think this story is great as it it, and yes, that includes the end point. Aside from the fact that the extras "hint" a relationship of the kind we were here for (it's pretty much evident), I mean, because you could ignore them and even then the only possible way for them to go would be becoming a couple.
Misono couldn't be more obvious if she confessed (seriously, "That will do for now"?), and Yuri's just oblivious from beginning to end. Their relationship progressed a lot in a short time, though, and as I see it the whole development made it seem as if it would progress to romantic sooner rather than later. And we already saw that, apparently, they started dating while still in high school. Meaning, it couldn't have taken them more than three years after first meeting.
As it is, anything more could've been excessive, depending on the... management of the story. Mind you, all this doesn't mean I wouldn't have liked more, only that we've seen how things can turn out when the story is stretched too much. I'd rather have it end here than have it go in circles for another lot of chapters.