Being shady about it is the tragedy, the part that most damages a relationship. Openness and honesty is the best. Talk about things, if you come to an agreement fine, if not, then part ways. Wives who cheat want both the security of marriage and the freedom to play. If playing is more important, then they should take the risk of losing the security of marriage by honestly stating their desires.
I think it is a little different for some men who cheat. There are men, and I count myself among them, who feel responsible for their wives' well being (mostly financial well being, also medical and psychological well being) and get no affection from them. I'm sure that many such husbands share my dream that she find a rich lover (male or female) and runs off with him or her. I would shed some mock tears, but mostly celebrate my liberation.