Despite her acting the demur wife with me, my wife had a long habit of showing off to guys. A chief part of that was sunbathing in her string bikini in the public areas of the flat. Unfortunately for me, that habit did end up on a number of occasions with my getting cuckolded; a great thrill now. So tan lines were for a long time a standard indicator of her desire to attract guys, and add to my cuckold crown.