The suitcase in the ditch is what baffles me.
I can very easily believe that a 19 yr old, living with her fiancé, across the country,and being dependent upon her financially, MIGHT feel a bit trapped and uncertain about how to make changes. Very easy to believe a 19 yr old could just 'bolt' and try to start over while figuring things out. And I think they'd eventually reach out to family, friends, loved ones to explain , apologize etc.
But the suitcase in the ditch does not make sense with that scenario. Not unless she had 'help' from someone with a vehicle who had ties back in her hometown area. But if that is true then I'd think LE would know that by now from cell logs/Social Media? But why would she dump her stuff like that? Why not just lay low and think things through if you just need a little space?
To me, that suitcase spells desperation, urgency, and trouble. It is possible that she had someone that she considered a friend to help her run away. And maybe that person was not trustworthy at all?
Then again, maybe she never made it out of the Spotsy area?