I feel like this is a design preparing us for a longer style of story. I think it’s unrealistic for people to be so forward especially at the developing age. However I do agree that if the author dragged on the oblivious cliche too long it becomes exactly what you are saying ( I.e...
The manga Is fire. I think that the ending though overall unsatisfying is relatively realistic because of how freaking awkward highschoolers are. Still it made me want punch A hole through my nearest wall.