primary elements: incest, cheating slutwife
along the lines of: housewife and mother, fit, likes to dress demure but sexy (light sundresses for example). She honestly loves her husband but also craves sex all the time resulting in her cheating. She would never instigate an encounter but would also never turn away from an expressed/implied interest, easily allowing herself to be seduced by the male's words/actions as long as no one else witnesses (ie she is discrete - doesn't want her husband to find out or rumors to spread). No other restrictions on who she cheats with: sons, nephews, in-laws, neighbors, friends' spouses, husband's boss/co-workers (assuming she trusts them to keep it discrete), teacher/principal/coach at sons' school, manager at local grocery or other shop. In essence: she is a nympho whose only restraint is discretion so her husband doesn't find out.
Most stories I see about a cheating wife have several problems that keep them from meeting what I am looking for: there are problems in the marriage (no love or little to no sex), cheating usually shown as a single incident, a series of incidents with only 1 or 2 partners, or a gangbang, and there is usually a distinct lack of discretion involved.
Bonus: if first cheating episodes happen at or immediately after wedding making her realize her need for extra sex and the excitement of cheating as well as the need for discretion. I could see such a story spanning 2 or 3 decades easily consisting of little vignettes detailing each time she succumbs to a new partner in her cheating. That is primarily the draw for me in such a story: not the repeated sex scenes but the different lead-ups, the seductions, and each time her realizing the renewed thrill taking a new lover gives to her.