Eh I'm always a sucker for sister fuckers, and this one doesn't have a harem tag for the simple reason to be a harem every member has to be aware of each other and fine with it. Ruby doesn't seem to be the sharing type willing to go THAT far (at least when she's not drunk). If anything it's missing a cheating tag, I seriously doubt she'd simply ignore it if she found out the MC kept fucking their mutual friends and their mom too behind her back after they became an official couple. I'd think if you don't wanna risk an eventual bad ending it's probaly not wise to fuck every pink hole possible if there's no harem tag (reminded of a few such AVNs, like Where The Heart Is, eventually you have to pick one LI if you don't want the opposite of a harem with everyone instead hating you).
