so let me get this right, her friend gave her to a guy she doesnt really know that well (What other people see) when she was off her shit drunk, alone, to be taken home. Sounds kinda sus
I used to not like ecchi and smutty manga but now I appreciate the rocket progression as opposed to it taking actual years before they even know that they like each other.
Throwing this out there, maybe the spirit that possessed him and her is someone he used to know, and he feels responsible for their death, hence the "Am I allowed to have [this kind of feeling]" remark.