Huh, this manga is going downhill, slowly but surely. Makes zero sense for them to act like that... how is sex going to distract someone from an exam or somehow impact them negatively? NOT having sex has been nothing BUT a distraction for them. It's insane. I don't know who the mangaka is... but it's seeming likely that it's just some virgin chick that doesn't know how normal humans act. It feels very... like pseudo-religious, "stay pure" nonsense to me. It's rough man.
What a shame, what a shame, what a damn shame.