I would go along with this if it were changed to "If you you wouldn't tell your partner about it, it would be cheating." There are things you can know about and be OK with, but rather not see. If I were at a party without my wife, I would dance with other women. But if she were there, I would usually only dance with her, because it might make her uncomfortable to watch me dance with another woman. (unless she asked me to dance with some other woman, which she sometimes does.).