Okay so i have a new Jill Izabella theory-
In my previous Isabella crazoyed theory I fucked some stuff up mostly the fact that I thought Jill's dialog were questions, but they are in fact statements. I now believe that mayhaps Jill put the moves on Isabella and though maybe Izabella was either hesitant or outright refused her advances her husband walked in on the altercation and left.
This brings you to ending of 0.8.2. Where if MC woo's both Jill and Izabella ultimately choosing Izabella she cry's her eyes out losing both her love's at the same time, but if you Woo only Izabella she still looks distraught over losing Izabella and ghosts everyone.
This all comes from a scene where Izabella is uncomfortable sleeping with Jill, previously I thought all Jills statements were questions leading me to believe maybe Izabella had been in a situation before like the one she's currently in with MC but now I think it delves more into what if every time she see's MC flirt with Izabella, Jill makes the weird distraught shocked faces it's not over the MC or at least not ONLY over the MC but also Izabella.
This explains Isabella's "I've become what I hate an adulterer" comment as she was previously condemned for this due to Jills actions. It of course could be it was mutual and the understanding they agreed to was like MC's understanding with Izabella it was a onetime thing though unlike Jill MC didn't accept it being a onetime thing.
^I'll also poke holes in this evidence for you. You walk into Izabella being invited to dinner at the Burks in hopes to get her in on a threesome to spice up their sex life she could be saying she put a stop to this action and it could have nothing to do with Jill being the friend she's referring to. Although Izabella Dislikes Jade presumably and something tells me she feels any better about our old pal Stephen so I don't know why either would fit into a friend slot in her own thoughts but who knows could be.