I've been busy irl thanks to my job lately, but if I remember correctly, Chloe is the one that's fighting MC's influence and has a little sister that he took in and can spend more time with her now, right?
Bimbo state gets unlocked by an event involving her.... ability, I forget how to trigger it, but it's similar to how her other states work once you get it. Her real self is predictably not pleased with the addition.