Spoiler alert. Hibike! Euphonium is one of my favorite animes of all time, no doubt. But, since I'm quite romantic, I'm always hoping for a relationship between the main character and someone who changes his/her life. This time, as the majority of Euphonium watchers, I was waiting for a relationship between Oumae and Asuka. I didn't expect one with Reina because it was obvious that they were just friends. And I'm not the type of person who's always romanticizing a relationship for superficial things. I actually pay attention to what leads up to that relationship. It doesn't make sense to methat Oumae wants to date Shuuichi. They're only long-date friends and he doesn't really have that much development during the whole anime. He's always in the back acting like a walk-on and looks at Oumae now and then. Out of a sudden, they wanna date just because? Asuka did a better job caring about Oumae and changing her life than Shuuchi (as far as we know).
Hope there's an explanation for that in the 3rd season...