There would have been no problem in her leaving. If Jonah was angry about Max and blaming it on RZ, all she needed to do was pack her things and move back with her sister/family or return to AZ. She was a very attractive young, healthy, intelligent person with education, skills and job experience.
That's probably what she intended to do. Perhaps her killer knew her plans and thought it was his one last chance to indulge his sexual fantasies.
BBM. Wow! This definitely falls in line with my theory about AS and what happened that night.