'Cuckolding' is a weird fetish that has become popular in recent years.
Men are encouraging their wives or girlfriend to participate in a sexual encounter with other men, according to a report by The Sun.
On Reddit, people have taken to the online forum to share their experience with the kinky practice.
For one man it was a "pure unfiltered sexual thrill" when he witnessed his girlfriend having sex with another man, The Sun reported. While others felt an "intense" sexual thrill when their women refused their advances.
While most people would see this act as cheating, one Reddit user pointed out there is a distinction when it comes to cuckolding. "There's a difference between cheating on you and "cheating" for you," the individual is quoted as saying in the report.
So what is the real drive behind it? Some psychologists suggest that it could be male bisexuality that is repressed or a partners' sexual freedom is appealing.
However, Dr David J Ley author of Insatiable Wives: Women Who Stray and the Men Who Love Them, sees the motive as being much more simple.
Watching their partner getting a thrill from another man may be associated with breaking the traditional relationship rules, which is turns them on.
"When an otherwise well-controlled heterosexual male dares to visually create his wife’s violating her marital vows, and possibly his even encouraging her to do so, he’s playing a vital role in what we might call a 'double transgression' of society's norms," Dr David J Ley told Psychology Today. He also feel these "forbidden fantasies" could be gratifying.
