Family search has 2 Denard marriages in Haralson Co. in that time period:
George W. DENARD married a Sarah J. CARTER on 10 Jan 1881.
James DENARD married Elizabeth WHISENHUNT 26 Sept 1884.
Also consider if the marriage was held outside the county - such as an elopement or at the home congregation of the other individual. Since Haralson County sits on the state line you should probably also look at records in Alabama.
Alternatively you can try contacting the Haralson County probate court who should (theoretically) be the custodian of such records: http://haralsoncountyga.gov/court_services.html
Local libraries also often have genealogical information such as: http://wgrl.net/haralson-county-genealogy-resources/buchanan-library-genealogy-resources/