Michigan is an equitable distribution state and like other similar states, you don’t need to include him on the refinance; however, he may have certain rights if it is his homestead:
Michigan homestead laws inure to the benefit of husbands and wives. With respect to homestead property, one spouse, acting alone without the signature of the other souse, cannot create a valid lien upon any interest in the homestead. The only exception relates to the granting of a purchase money mortgage. Michigan Constitution 1963, MCLA 600.901.