I don't like it he got raped
That’s call consensual non-consent, and that type of play is discussed ahead of time. That’s a fav play of mine, but again, in the majority of spaces everybody in the act consented at some point in time to do that another time. Additionally, in that type of play, there is a safe word established to make sure people stop when you want to. None of that was done in this manga, but it is a thing like you had mentioned.
Finally a bl where the main character respects consent and does'nt just kiss and fuck on there own accord ლ(´ڡ`ლ) I like ittttt