Id probably find it asked somewhere in the archives, but since im lazy, ill ask again.
In a very broad sense, cheating involves betraying a partners expectations about the type of contact the cheater has with others. When a husband or wife, boyfriend or girlfriend, violates ones expectations about what is appropriate, people feel betrayed.
what is your definition of cheating on your spouse, boyfriendgirlfriend? I personally define cheating as any intentional act with another woman that i know will hurt my wife. I know thats a very wide brush to paint with, and im fine with it.