they are not a couple... if u pay attention, even tho Uminconfessed, Maeharanis still holding back taking this important step, but he clearly likes her.
You guys are rushing a bit much, because this arc ia teasing already what is this "ghost from thr past" that he needs to fix before jumping into this relationship.... the thing is Umi is ok with waiting, but dont want to hold back at the same time lol.
Just recall how thirsty they let Yamada get in BokuYaba. And there's still more of that to come in S3. (Including the now-infamous love hotel visit. And those were middle-schoolers. Have faith.