This is so interesting... It was actually very good and absolutely disturbing. This is how Stockholm Syndrome works.
The guy forcefuly invades the MCs life, mines his mind, harasses the people that are around him that could provide an escape and shows absolutely no regrets in doing so...
Oh, let's not forget the psychological violence. It's in every bit of this manga... then comes the sexual one.
It's disgusting. Really. And yet, the mangaka makes this story so intriguing that you must keep reading.
Personally, I'm disgusted by the fact that they are togheter, and yet, I believe in this end.
Great work, mangaka!
And, as the story goes, the characters become more... palatable?
Truth is... Ina Shuhei is not "true to himself", he is a manipulative jerk. The husband is gay and repressed and full of trauma, but the 3 of them are just a combo going towards a bigger disaster.