Pretty sure we have an author who does not know their audience. Despite the dense amounts of nudity, this has been a pretty vanilla ecchi harem isekai series. While teasing things like rape and NTR in such a series is nothing new, actually fully committing to it is another thing entirely.
It just got done with what was already a poorly received arc with the scumbag prince, so getting zero reprieve and diving headfirst into what is essentially an entire other genre, and one not very popular with general manga readers, is a very gutsy move. It might not have been so bad for people if the theme of NTR was less, but the MC clearly has a loving relationship and was ready to give his virginity (as many people have pointed out, the titular character trait of the series) to one character and may have been open to accepting a harem with two other long-standing characters. Now, however, that has been completely derailed by a rather whiplash-inducing rape scene. It's not surprising that it would heavily sour the series for fans, or even casual readers, of the series.
The best we can hope for at this point is the author has some kind of solid plan for where the story is going, or else could suffer a harsh decline similar to
Survival in Another World with My Mistress! after similar themes, except that one was way less vanilla.
Tl;dr, know your audience.
