Welcome to Websleuths!!:seeya:
The only thing that causes me to disagree with you well spoken post, is that Rebecca had family and friends. She wasn't isolated or without places or people to turn to.
I would think if she got a text or phone call, that she would have been very upset, but I have a feeling she was close enough to her sister, that she would have called her.
She had been through a breakup before and was 32, I can't see her sinking into a depression deep enough to commit suicide in a matter of hours.
This is of course IMO, and based on what I have read only.
Thanks again for posting and welcome!! I'll look forward to reading more of your posts!!
The phone records would show if JS called or texted RN after her phone conversation with her sister. But I am not even sure they would have access to his phone records, considering he isn't even a suspect or a POI.