The original meaning of cuckolding was a married man who's wife was having sex with other men. That was it ... the definition. It didn't matter if the married man was aware, unaware, resentful, heartbroken, angry, overjoyed, jealous, etc etc,etc. The fact that his wife was fucking other men made him a cuckold. Often the final outcome of the marriage was not good ... divorce or worse, since basically cuckolding meant "unfaithfulness" and was a public embarrassment to the husband. Back in the days of original cuckolding, a wife served a secondary role to a marriage ... she cooked, cleaned house, had the *******, etc and was not to be an embarrassment to the "family providing" husband. Disloyal wives were often publicly scorned.
Over the past 15 or so years, however, cuckolding has taken on broader meanings. It now applies to both men and women who have spouses that are cheating on them ... ie: Sandra Bullock & Elizabeth Edwards both referred to themselves as being cuckolded by their cheating husbands. It is now applied to
unmarried relationships, not just married, where the couple is suppose to be in a monogamous relationship. And, cuckolding is often initiated by the husband's request that his wife have sex with other men. So, cuckolding has become a voluntary, as well as an unvoluntary, act of infidelity as some couples find cuckolding stimulating to their own sexual relationship.
Couples have started customizing their own brand of cuckolding, however, by adding fetishes such as cocklocks, sex denial, bareback sex, forms of humiliations, domestic & subservient service, sissy dress, milking, interracial sex, cuckold amendments & agreements to the marriage contract, pregnancy risk, creampie eating, etc etc ... the list is long and still developing. Couples pick and choose those fetishes (sort of like adding features to a new car) that they find stimulating to their own cuckold lifestyle. The whole point to all this is to add stimulation to their sexual relationship or to provide a sexual service the husband is incapable of providing. Every cuckold arrangement is similar, and every one different, to some degree. Think of it as a "one-sided swinging" arrangement.
That's as "condensed" as I can make it ... hope that helped some. My wife and I have been into swinging 19 years now ... but never gone the cuckold route.
Mac