"  WE'LL BE TOGETHER AGAIN"  Composed in 1944 by Carl Fischer, pianist and conductor for pop singer Frankie Laine who also provided such touching lyrics.
The song meets the demanding "quality criteria" of the Great American Songbook and also achieving popularity with a mainstream pop music audience.
Additional bonus. I have provided two versions, the firsr by Ella Fitzgerald, the second by Frank Sinatra. How fitting since Ella and Frank have recorded more high quality songs of the Great American Songbook than anyone other than  Tony Bennett.
I believe Ella's version is the most tender and sympathetic performance of the many hundreds of songs I've heard her sing. She provides a slightly more optimistic tone than Sinatra, that superb singing actor, who conveys a world-weary sadness despite the promise of an eventual  reconciliation with his loved one.
Sinatra has described himself as a manic-depressive, with his depressive side perhaps on display in this performance.

 https://youtu.be/mrFkyEG7eWw

https://youtu.be/o1Ty13_juCc