I think this is a classic case of comparing...um, two fruits that are different from one another. Promiscuity and cheating are two different animals. This "group" is "noteworthy for its tolerant attitude" towards promiscuity, casual sex, etc., not marital infidelity. Unfortunately, these two things intertwine with one another, most frequently under deception on the part of the cheater. Hence the wildly spraying hostility regarding the topic.