he did get raped tho, the mangaka just decided not to handle this as actual rape. luka didnt wait until he got explicit consent before advancing on hayato, which constitutes this case as rape. luka ignored hayato's requests to stop, which constitutes this case as rape. luka forced hayato to engage in a sexual act so that he can prove his love for him, which constitutes this case as rape.
the reason why it might had been difficult for some people to recognize that this is rape is because the fact that yaoi mangas tend to normalize rape as a genre. its necessary to know that if there is no explicit exchange of consent before a sexual act is engaged that rape will most definitely ensue.
Nice to read a yaoi where the uke doesn't get raped and develops a Stockholm syndrome. (▰˘◡˘▰)