oh ew, they're really romanticizing wanting to fuck someone with the mind of a child.
The way I see it (atleast at the moment and only based on my current interpretation) it’s not too messed up to me.
I think it’s normal to feel a attraction to a grown persons body, and I think he’s imagining/projecting some of her actions onto his visualization of her body and how she could’ve been if she was fully mentally there. He (to my understanding) is not attracted to the part of her that is not mentally there, which I think would’ve been weird if so, rather he just sees a grown women do something which would normally be a bit sexualized, and has to tell himself to disconnect viewing her based on how she may’ve been if things were different based on her body’s appearance.
I do think the manhwa could’ve portrayed it a bit better if it is how I understand it, as the emphasized blush at the end is a bit much if so, but it’s a common visual indicator rather then necessarily being him massively blushing.
While this may not be the case and may change as I read more, they’ve also shown a few instances of her on her own after something happens where it is semi implied that she understands some more then she lets on (atleast I think that’s what one of the lip bite images after he left the room a chapter or two ago was trying to imply). Not that he could know this, but I think taking the series in as a whole, while right now it may be weird that the author included any level of romantic feelings, it could be moreso something that comes into play later if she is shown to understand more.
I’m unsure the normal view of it, but while she isn’t fully there, it’s not as if she is a child, she can’t consent but she has lived for 20 years regardless of everything else, I think she still is allowed to be loved, if it’s not weird / forcing something on her. Romantic feelings != sexual feelings.