Cute, wholesome children as always
But when are you gonna progress with the romance? You’ve got a romance tag, do something with it!
Unfortunately, I think in the last chapter it had the central focus (which was a long time ago so I don't remember the exact number), the author handled it in way that was pretty much them saying, "Ryuuichi's focus is on his brother right now, so don't expect that kind of development anytime soon when that isn't even the point of this series." I don't think it'll ever be really addressed again as long as the manga continues being serialized. They've essentially anchored the ships in hopes of never having to address it again or at least for a long time, just like in QED (if any of you have read that).
Case in point, look at the two girls. Ushimaru is still blatantly crushing on Ryuuichi because that was her initial characterization with little else. However, she hasn't really gotten closer to him at all.
Inomata's crush on Ryuuichi, on the other hand, was downplayed to the point of near non-existence if any, and the only relationships she has that get any focus are the ones she has with Ushimaru and Kirin.