Infidelity Was A Way of Life With The Split-Level Dwellers
A novel of women who traded husbands — of men who borrowed wives — of couples who embraced adultery with feverish delight.
This cover looks suspiciously similar to the cover of Change Partners. The 1963 edition is here
Harry Barton’s cover, reversed & reworked :
https://pulpcovers.com/change-partners/#1