Welcome to the "hotwives" community. The theme of this community is men whose wives/girlfriends have sex with other men with the consent of the husband/boyfriend.
I run a similar community called "cuckolds." So what's the difference? Well, cuckolding leans more towards the humiliation and domination of the husband/boyfriend by the wife/girlfriend and her superior lovers/bulls. On the other hand, in hotwifing, humiliation and submission of the husband/boyfriend are not common elements.
So join whichever community you're most comfortable with, or both. Post thoughts, share experiences & fantasies, meet others who are interested in the lifestyle, etc. You must be at least 18 years old to join. I get to decide who gets to join and then who gets to stay in the community. But, I'm pretty easygoing so long as you're over 18, don't post about illegal activities, and are polite to fellow members.