Frances Deitsch was born in Manhattan on Oct. 21, 1927, attended Temple University and the Fashion Institute of Technology, and fell in with the group that came to be called the Beat generation. She thought Kerouac was "the best-looking man I’ve ever seen," and the feeling seemed mutual. He and Allen Ginsberg serenaded her with bongos. "Be my girlfriend, I’m so lonely," Kerouac pleaded.
The obit goes on to chronicle her unusual marriage arrangement with husband, Jay:
They were wed for 61 years; Mr. Landesman died at 91 in February. They had a remarkably open marriage in which each brought partners home to sleep in separate bedrooms. Everyone then had breakfast together. Their teenage sons, Cosmo and Miles, were appalled.
Apparently, she finally gave up that behavior:
"When you reach 60 — forget it," she said in 1998. "I think it’s unattractive after that."
One of Landesman's songs, "The Ballad of the Sad Young Men," became a jazz standard and was covered by Petula Clark, Robert Flack, and others.
Seems like she would have shown up in one of Kerouac's novels (by a fictional name, of course), but I can't confirm that. If you find something out in this regard, please let me know!