All the people have seen spoilers unlike you xD
Even if it was spoiler, do you think it's nobody here watched/read Game of Thrones? Nobody's ancestors were cousins? Oh please, it's absolutely greatly written MEDIEVAL story. I'd feel worse for reading isekais of how sweet woman's life was there.
The world isn't a perfect place so stop being in denial, people read it for the story, it's not even mature content
interesting how ppl are still saying its not incest.....when it is as clear as daylight ...all these ppl be like feeling guilt for enjoying it and is in denial...