Civil registration and church records in Italy were kept at the town level. You did not say when the marriage took place, but if it was 19th or early 20th C the Family History Center in Salt Lake City has microfilm copies of many of these records. Many have been digitized and depending on the town are available on-line or by going to your local Family History Center (when they re-open). To find what records are available go to familysearch.org, then to search, and click on catalog. Search by the name of the town and a list of records for that town should appear, if they have them.
Dear Ms. Sweeney,
Thank you for posting your request on History Hub!
The National Archives and Records Administration (NARA) is the depository of the permanently valuable non-current records of the United States Federal Government. Under Italian law, records of births, marriages, and deaths are maintained by the Registrar of Vital Statistics (Ufficio dello Stato Civile) in the city (comune or municipio) where the event occurred. There is no central, regional, or provincial office established which keeps such records. Please review the FamilySearch Research wiki for Italy Civil Registration and the U.S. Embassy in Italy webpage on Obtaining Vital Records for more information.
We hope this is helpful. Best of luck with your research!