An inequity

I wouldn't dream of copying someone else's answers on homework or bringing a crib sheet to a test. I would never be unfaithful to a partner. It wouldn't occur to me to move my board game piece while my opponent was in the rest room or cut in line for an amusement park ride. Yet, I frequently sabotage diets, break rules I have made for myself, and look up easier ways to get through levels on a video game that is frustrating me (or, more often, hand the controller to my husband to get past the frustrating part for me) so I am obviously not opposed to all forms of cheating as long as it doesn't hurt anyone but me.
I have always thought that I believed all forms of cheating to be wrong, but I guess I don't. Don't tell my students. In the classroom everything has to be black or white, but the real world has shades of gray and times when self deception isn't so terrible. Is there such a thing as a white cheat like a white lie? It is still an inequity because you aren't strictly abiding by the rules, but it isn't an iniquity.  It is interesting to me that I don't cheat unless I am the only one with something to lose if I cheat, yet it upsets me when other people cheat me especially if it causes me to lose money, time, self-respect, or a good grade. So, I don't believe that it is okay for anyone to cheat as long as I am the only one cheated. Other people aren't allowed to use dishonesty to deprive me of something just like I am not allowed to deprive them of anything through dishonesty. Still, I would encourage people not to cheat themselves even though I do it so I guess I have a bit of a double standard.