I also learned about wife sharing and cuckolding from reading Penthouse forum letters. Then one day in the 1960's, I spotted a new men's magazine at my local newsstand called Gallery Magazine. It appeared to be entirely centered on wives having sex with men other than their husbands. In addition, a lot of the stories were sent in by husbands who proactively wanted to watch their wives having sex with other men. Penthouse photos were always of "professional" models that ordinary men would not have a chance with. In contrast, the main photo shoot in Gallery was entitled "The Girl Next Door" and displayed nude photos of wives sent in by their husbands. Identification was usually "Jane B by her husband John". The women were not center fold or trophy wife material but were of women who would be seen on the street, in a store, at work, on vacation at the local beach, teaching in the local schools, etc. But they all had one thing in common, they were wives being displayed in the nude, their legs spread wide, and their married pussies on full display. The published stories all had a common theme, a husband wanting to watch while his wife had unconditional sex with a stranger, with the stranger shooting his full cum load deep into the wife's married cunt. If the stranger was a Black man, it would be said the wife was going to be "Soul Screwed".
The word cuckold was used to describe a married man whose wife was cheating on him, with the husband being clueless to his wife having the cocks of other men thrust into her fuck hole. Gallery generally used the term "Wife Sharing" to describe a husband who wanted to watch his wife commit adultery and get sexual pleasure from such voyeurism. Over the course of time, the two terminologies would be treated as meaning the same thing. As different circumstances became known, words such as "Stag" and "Vixen" grew in popularity.
The attached photo of my wife in our martial bed was typical of what was published in Gallery Magazine.
