Haru really can't help torturing herself with this crush, can she? Eventually she'll tell him, but not now, not yet. But she knows he won't reciprocate.
it started becoming insufferable 50 chapters ago
50 chapters ago was in the middle of the arc about Shu's crush on Kyoko-sensei. That was a painful, but good, arc. It was made into one of the best episodes of the anime.