To be fair, I'm pretty sure none of the women that can eventually join the poly/harem route ever say they're straight or not attracted to women. Heidi and Athena are obviously already into women. Mora or Sadie have no real sexual experience and little dating experience, so it's not too unbelievable that they might not have figured out their sexuality yet. Also, when you mention to Mora that you're also dating Heidi and Athena and they think she's hot, the game specifically mentions the MC noticing her nipples getting harder and her dialogue, while conflicted, appears more intrigued than alarmed at the idea (this is all before the MC and Mora have sex, much less her joining the poly relationship). Minor details, but they do make the whole thing a little more believable to me at least.