I think it's because that red haired dude gave him aphrodisiac so he's not himself plus suha was almost raped on the same night :( hinana
i think it’s more because suha just looks like he doesn’t want to have sex at this moment because of the red head he looks more like he want to just sit there and be worried about his partner idk that my opinion
i don’t know why but this chapter make me feel very uncomfortable