So I unintentionally bought an out-of-state duplex site-unseen.3).

Here is some of the most important points in deciding WHERE to invest your money as a private or hard money lenderResidential O/O - Heavily regulated, easy to run afoul of regulations inadvertently, severe penalties possible even if non compliance was unintentional, possible bias against in court, compliance with regulations biased on side of borrower, compliance issues Federal (lending issues) and state (Homestead protection for borrower).Residential Non O/O - Medium regulation, regulations easier to comply with, penalties for unintentional non compliance less severe than above, possible bias against in court, trap is believing loan is non consumer when it actually is consumer or BECOMES consumer after the fact, compliance issues both Federal and state (but not Homestead).Commercial - Very light regulation other than as to securities issue determination (which should not affect lender that doesn't sell the note), penalties for non compliance not severe and much easier to rectify, most compliance issues state not federal, less bias against in court.So, IMO, the ONLY reason to make SFR loans (residential loans) is that you, as lender understand the property type better than you do commercial property.  

My husband, Lucas, and I are just about to sell what I call an unintentional flip.  

I guess I mislead you, unintentionally I might add. 

Tenants sometimes make unintentional mistakes in managing their money.

@Jason Wu, if the property is located in California, be aware that you may unintentionally cause a re-assessment of the property if you transfer/add yourself to title.If your partner is trustworthy, one option is to form an LLC with your partner (again probably California LLC if the property is in California), put this property and subsequent properties into the LLC, do proper accounting for each property in the LLC, obtain sufficient insurance, and operate your properties prudently and reasonably. 

I do not see the lender approving the loan unless someone dropped the ball unintentionally?

Well done Oregon, now everyone loses  :) agreed unintentional consequences or to say it another way a bone head move with no realization to what the free market will do or will react like

This is how, unintentionally, I got into real estate investing

This is where most owners unintentionally cause delays.