I honestly don't think I could pick just three. Just the thought of breaking any of their hearts makes me feel like the biggest heel on the planet.
As for "why do so many people care about incest" - I'm okay with it not being in this game, personally. It's whatever. I do enjoy incest in games, though - oddly not because of the taboo factor, which is what a lot of people are into as I understand it. I just find that once that taboo is broken, the family members you're with have an extra level of being into you that I often don't get without incest in a game. The women just seem to be down for anything, and soak up your presence like an addict getting their fix, and personally I can't get enough of *that*.
In this particular novel, I do wish Willow/Cedar were a love interest, because she'd definitely be absolutely everything in my paragraph above, and she's very sexy. I'm less conflicted about the mother figures. Still, I'm not going to start clamouring for it to be included. There's plenty of awesome LIs in this novel without them.