I totally ship natsuo-hina's relationship from the start but i respect others readers opinion on natsuo-rui's relationship...i could the plot is similar to a anime when hina sensei left and while natsuo became dull for a while is similar to (anime:rumbling hearts)
Chapter 68 is missing
It was just never uploaded, you can find it on the scanslators page and download it or go here http://mangakakalot.com/chapter/oujisama_nante_iranai/chapter_68
Im looking for a similar manga but more explained in their personal life besides their relationship if you know it by chance let me know
Virgins Empire
And theres a non yuri one, tsuredure children