There is a Jacob W. Miller listed in the 1850 IN Census for Delaware Co., but no Nancy listed.
In the 1860 Census for IN, Delaware Co. lists the following Jacob Miller's: Miller, Jacob; age 20 b. IN Miller, Jacob; age 43; b. OH Miller, Jacob; age 54; b. VA
Miller, Nancy; age 42; b. OH Miller, Nancy; age 55; b. OH. The only Jacob and Nancy in the same dwelling and family # are Jacob age 54 b. VA and Nancy age 55 b. OH and the following is the info for that dwelling:
Miller, Jacob, age 54, b. VA, page 0538, line 32 A, Monroe Twp., Richwoods P.O. Miller, Nancy, age 55, b. OH, page 0538, line 33A, Monroe Twp., Richwoods P.O. Miller, Henry, age 22, b. IN, page 0538, line 34A, Monroe Twp., Richwoods P.O. Miller, Thomas, age 16, b. IN, page 0538, line 35A, Monroe Twp., Richwoods P.O. Miller, Milla (female), age 16, b. IN, page 0538, line 36A, Monroe Twp., Richwoods, P.O. Miller, Jefferson, age 4, b. IN, page 0538, line 37A, Monroe Twp., Richwoods P.O. Miller, John, age 2, b. IN, page 538, line 38A, Monroe Twp., Richwoods P.O.
Trying it from a different angle, there are Catherine Miller's listed in the 1850 Census for the following counties: Cass, Daviess, Henry, Jefferson, LaGrange, Miami and Ohio. All I have is the index, so I don't have ages or any further info for the Catherine's listed in these counties, but if she was still unmarried in 1850 it may be worth further research.
In the 1860 IN Census there is 1 Abraham Hale listed, age 5 and 1 Catherine Hale, age 31, b. Germany.