I found a clue.
In the 1941 Atlanta City Directory, p. 321 (at ancestry.com)
---Trilla Mrs waiter r625 Crew st SW
I know this is Trella because the address is her parents' house. They are also in the directory.
This implies that James is already gone by 1941.
The Jas M Harlan (wife Louise) listed is NOT her husband because he's also in the 1938 and 1939 directories as an insurance manager. Trella's husband is a house painter.
I'll keep looking...