Actually, it's not. There's 2 variables set up for harems in the code. One for Ash's harem and the other is Jen's. So, the dev is making it reality.
Well since you have already taken a look, would you mind telling me who's in Ashley's harem and who is in Jen's? I'll do solo paths eventually, but I'd like to get my harem runs out of the way first, and since Jenny and Ashley are mutually exclusive, I'd like to know who I can go after while on their paths and who I can't.
Also, my 2 cents regarding turning straight girls bi, I could be wrong, but if most/all the girls are straight and not in the least bit bi-curious, Jade proposing a throuple/polyamorous relationship could just be her, desperate to be with the MC, knowing she doesn't stand a chance head to head against Jenny, coming up with this solution if it means they all get to be 'with' the MC, proposing something sure to entice the MC into an open relationship where he essentially is being shared by multiple LIs, who may be willing to participate in a threesome just to convince him to give this arrangement a chance.
If Jade and Jenny really don't swing that way at all, they may agree to having sex with the MC with the other present, without actually interacting with each other...essentially just taking turns and at worst they would see the 'other' LI naked and having sex with their shared boyfriend (MC). I would honestly prefer completely straight girls to remain straight and agree to just taking turns with the MC during sex without forcing them into having sexual/romantic contact with each other.