circle violation
When you have sex with more than one person in a circle of friends or coworkers. This act may disrupt the natural balance of this circle of acquaintances, causing discord, animosity, and jealousy among the members of the circle.
Jane slept with both Ted and his best friend and former fraternity brother, Larry, which was a blatant circle violation. Although neither Ted nor Larry are interested in dating Jane, they no longer speak.