It's best to consult with a real estate attorney or financial advisor to understand all your options and potential implications.

so... what if you :-ignored the headlines-were an individual in a strong financial position-bought an STR in a place you believed in and liked to visit, and-were willing to put in some time, effort and funds over 1 or 3 or 5 years?

Based on your description of the situation, you're not going to cashflow while you live there, but the question you should really ask is, will it cashflow after you move out? 

Given the situation, I'd say it might be worth considering the long game.

It is important to consult with a legal professional or financial advisor to fully understand the implications of assuming the mortgage and how it may potentially affect your financial and legal responsibilities in the event of unforeseen circumstances such as her mother requiring care.

Feel free to DM me and we can speak on this further, it is one of the most common situations we deal with. 

If I see this continuing do I offer a a cash for keys situation to just get her out?  

You could offer them 1/2 or whatever ratio you feel is fair given the circumstances and they can write you a check for that amount to walk away.Another thought, if there is a way you can find out where they are moving, a forwarding address etc, I'd reach out to that new LL or owner and explain the situation to them, I have a feeling the tenant didn't disclose that they have an existing lease as a liability in their financials when the applied, and there may be some application fraud etc at play here that the new LL would likely want to know.Think about this from your own point of view, I doubt if you picked up and left one of your subway locations that the the LL would just let you leave.  

My current situation is I want to get into real estate but don’t know if I should go whole sale, agent, investor?

The biggest differences will be the taxable situation.