To me, "cake-eating" is when a wayward spouse gets some of their physical and emotional needs met by their OW/OM, while some of their other emotional, sometimes physical, and usually financial needs are being met by their betrayed spouse, without condition or consequence. When this condition is reached, there is really no incentive for the adulterous spouse to stop their infidelity, because they are "having their cake, and eating it, too."
"What is best for my kids is best for me" Amor Fati Link to quotes: https://www.divorcebusting.com/forums/ubbthreads.php?ubb=showflat&Number=2879712