@SW-User Have you recently read the Surviving Infidelity Forums? If the posters of the group had knowledge that their marriage was open or it's considered 'normal' to have a boyfriend or girlfriend in a marriage, those posters wouldn't be hurt and confused with the next steps of their lives.
People actually have feelings. Despite what other people may believe or want to think, there are people who actually are dumbfounded when an affair is exposed. People actually have feelings. People actually cry and look back over a life that was filled with lies. People can actually 'love' and 'commit' to marriage.
Are the people that you mention, consist of people who are betrayed or the ones who are either in or want an open marriage or the other woman or other man?
Reading stories of heartbreak over infidelity is real and a hurt is natural to 'people'.
I know that ow/om have been betrayed...they've been hurt over infidelity in a relationship but does inflicting that same pain onto others make cheating 'normal'?