(I should have just added this to my previous reply to you but since you can't fully delete a comment I'll just leave it here.)
It seems that he wants to hide the fact that he's boning Ruka from Aoi, or at least that's what I got from him thinking "
there are eight of them in the room but I don't want to use it" with the Aoi signaling "no" above the text box. I wonder how Aoi will react to the bloody sheets. She says that they are just "friends" (fuckbuddies although she probably doesn't think of it that way) and not BF/GF, but will she feel cheated on or will she want to jump in for a threesome?