Why doesn't Keesha trust Memphis anymore, oh year because she heard something Jerry told her. She also made new enemies when she didn't have to during her HOH. Michelle is much smarter than her.
Why does Renny hate Memphis? Because he hung out with Keesha and made her jealous by wanting to sleep in the same room.
I still don't understand why he's willing to risk Memphis leaving but not them. They're not taking him to the end but he is.
It also leaves Ollie up for an option, which would be the smartest move for Dan. Fucking Jerry and his calling Dan out and his religion has got to Dan's head and now he's afraid to betray people because he's worried about what people at home might think (they think he's stupid for not doing it).