This game makes me wonder about some things.
I don't like NTR or sharing. And in this game the MC is a guy from outside the family. And my favorite genre is incest. But I wouldn't mind if Alice and Riley had sex, after that mouth kiss between the two of them, it made me wonder if the two of them were already in an incestuous relationship. In that case I wouldn't understand it as NTR, since for me, incest would speak louder. The same would happen if Riley and Hailey also had sex, I wouldn't mind. Even if it were categorized as NTR, I wouldn't care and I wouldn't understand it that way.
Likewise about sharing, I wouldn't mind an MMF between the MC, Alice and Riley, or between the MC, Hailey and Riley.
Strange isn't it. I would actually love to see those scenes.