However, if I was renting a 1-bedroom to someone and 2+ new people move in I would be more likely to ask for a higher rent due to added wear-and-tear and a higher water bill. 

This time they will all go to auction for 'real', there is no redemption period and you can get to work right away mostly either tearing down and putting a build on it, or merely clearing and building. 

We went from being able to tear down an old staircase, to having to rebuild because of fire safety and its been designed now 4 times and we have to now redo all of the gas lines and close up windows. 5000 dollar project is now estimated 60k and growing.

When the relationship ends he will be your tenant.If you do not wish to fully screen him now and accept the fact that you will have two tenants you should reject the application.If you are on the fence tell her that due to the added ware and tear, water usage etc. you will need to charge her a couple of hundred more on the rent and see what she says. 

Since my cabins are small, that doesn't bug me; if they were 4BR+ I'd want a different timeline.Overall I'll happily sacrifice occupancy for a higher gross rental income month over month; fewer guests to deal with, less wear and tear on my cabins; but hopefully I can get it to the point where my occupancy stays up AND my ADR goes up.  

Dave Ramsey tells the story (If you don't know his story he was a real estate investor who went bankrupt in the bubble burst of the 80s) he tells the story of the debt collectors calling his house at all hours and harrassing him and his family, and how one of them said to his wife "How could you marry a man like that, who doesn't pay his bills" that put his wife in tears.

Plus, inspections are done annually and whether the damages each year are from a tenant or from natural wear and tear, you are expected to fix them immediately, whether you have the means to do so or not.

Not wear and tear.

She would not have lasted 40 years if she is a bad tenant or one of those that tears things up. 

Drive around it everyday and look for anything vacant, ugly or tear downs.