The art is amazing. I thought the artstyle seemed rather familiar, I believe this was the guy that made some of those monster girl releases that once were on this site.
And similarly to those, really makes me think about things.
I can't blame him for being overcome by grief and anger, but he did act like a bit of a prick, and even now he admits he is still one...But by that end, I'm not even sure why she is even with him, or what he meant by her satisfying her ego...It's confusing, but it's the good kind of confusing, that really makes you ponder.
For me it's not very surprising that she stays with him... to me she appears like a demoness from ancient stories who seduces men and gives them pleasure and guilt at the same time. Superficially it might appear that he is a prick that uses her guilt to make her do all sorts of things, but in fact she is the one who calls the shots. She decides that they have sex and she decides that they are not lovers. Despite that she always says that she loves him which makes the reader and him wonder how she meant it, brother sister platonic love or lovers love.
She knows that he loved her since childhood and she loves it to tease him and look how he struggles with his guilt and lust, knowing that he will never be able to escape her.
He simply is the perfect prey/plaything for her which leads to her never leaving him either.
It's funny how the other stories of the author are about monster girls who behave like normal humans and this story is about a human girl who behaves like a monster - not that I mind, I find the demoness/diabolic type of girls hot as hell...