Dear Ms. King,
Thank you for posting your request on History Hub!
The "official" photos of individuals, taken by the military, are not considered to be permanent federal records by the respective military services and are not retained by the service. If the photo you are seeking still exists, it will most likely be found in the individual's Official Military Personnel File (OMPF).
Official Military Personnel Files (OMPFs) and individual medical reports for those who served in the U.S. Armed Forces for the Vietnam War are in the custody of NARA's National Personnel Records Center in St. Louis. Many Army and Air Force personnel records were destroyed in the 1973 fire, but proof of service can be provided from other records such as morning reports, payrolls, and military orders, and a certificate of military service will be issued. Navy & Marine Corps OMPFs were not affected. Please have your fiancé complete a GSA Standard Form 180 and mail it to NARA's National Personnel Records Center, (Military Personnel Records), 1 Archives Drive, St. Louis, MO 63138-1002.
Photographs of various U.S. Army, Navy, and Marine Corps activities dating from 1940 to 2007 are in the custody of the National Archives at College Park - Still Pictures (RDSS). Please contact RDSS via email at email@example.com. The web site is https://www.archives.gov/dc-metro/college-park/photographs-dc.html.
We hope this information is helpful.