Can A Non Married Co Signer Go On A VA Mortgage?

This question comes up pretty often, A Veteran is seeking to purchase a home with a VA Mortgage and wants to add his girlfriend to the loan or vise versa. Maybe they are engaged and not married yet, sometimes the plans for the wedding are for a date that will come after the purchase of the first home. More often than not we hear lenders telling a Veteran that it is not possible to add a non married non veteran co-borrower to a VA Mortgage and that they must get married in order for them to both be on the loan. That is actually false, but there are a few caviats.