Up until recently, I would have said that infidelity is both immoral and disrespectful. Then I adopted the view that it was disrespectful but not immoral (if it could be guaranteed that one's partner would never find out about it) and now I'm not sure it's even that much (disrespectful).Imo, something is morally wrong if it either a) causes someone else to suffer or b) deprives them of pleasure/happiness. Cheating on your spouse, if it could be guaranteed that (s)he will never find out, would no