I think some of those who do allow it / or accept it/ put up with it will tell you its because their spouse is having a MLC.and its different rules!!! or no rules. It never happened to me and I know or think I know I would never have allowed it BUT I guess we have to walk a mile in their shoes to really know. Many years ago I did know of a woman who shared her husband with another lady she had the week other lady had week ends! it continued for about 20 years and it never bothered her until he came to retire and she confided to my mother she was worried he would leave her to be with Mrs week-end. No he continued as before until he died. They both had kids by him and he actually left the home to the children of Mrs week end who was not his legal wife. I am still amazed by this.