This is not a path constraint you're experiencing. My main playthru is now fully locked into Neutral affinity, but Jill was the only option for me.I'm on Neutral but there is no Jill option at the end. Only Sage, Isabella and Maya&Josy
It's the events and other girls your MC slept with that locks Jill off. Because MC himself cannot justify pursuing Jill if he's also sleeping with many other girls, this was a thing in Episode 7. It just got fully locked off in Ep8.
Also, Neutral path locks NO SCENES off with Jill. It's entirely choice on hookups and other events dependent. A mostly Jill centric Neutral run will have all of Jill scenes easily.