TLDR: A will to insure fiance inherits the house and enough term life insurance so finance can at least pay off the mortgage. Boom, done. . . First, make absolutely sure that any advice you decide to follow is in accordance with Indiana state law.

Second, seriously consider a short visit with a lawyer specializing in Indiana inheritance law. Initial consultations of 15 minutes or less are either free or low cost. Bring copies of your mortgage documents, title insurance, and any other paperwork from when you bought the house. Along with a written list of questions that you want answers to.

Assuming you have a will, take out enough term life insurance to cover the cost of paying off the mortgage, a years worth of property taxes and home owners insurance, and at least 6 months of utility bills. As well as the costs of probating your will and burial costs.

This way, your fiance won't have to deal with your mortgage company along with grieving and dealing with probate.

(edited for clarity)