RE agent does the showings and basic screening. after basic screening - when I am doing my screening from applicants , I take my time to try to CHOOSE as WISE as I can , meaning I am looking for long time relationship , with a tenant, a person, it is a relationship like nay other . if you choose smart - you will have a long time tenant , with no MIDDLE MAN. 

So here's my question:  Do rents tend to act more "rationally" (for lack of a better word) than home price appreciation and therefore rental markets are in general more stable and predictable?  

This is a shiny object of distraction, rationalized to look better than lipstick on a pig.

My reaction is that this is a bad idea.First, you are becoming a business partner with someone who does not appear to be in a rational state of mind. 

You're essentially a middle-man but you don't have to own the place out right. 

Or if it is move-in ready, refi after you buy (and after any seasoning period required by the bank.A couple of things you'll want to look into first:  Make sure your debt to income ration is so high that a bank won't do a refi. 

I think the bigger point is that FEAR isn't always rational.

does have a higher or lower cost or higher or lower interest rate change the way the seller looks at itI got the impression that you would end up being the middle-man, rather than the end-buyer?

You have to look at risk/reward ration ( what is my upside versus downside and conservatively how long will it take to get there?) 

@Allison PanilaI’m not sure if it’s legal for the landlord to raise the rent in your area ,but it’s safe to say your friend is breaking the lease and is trying to rationalize bad behaviors .Id try to get her and her boytoy out too.