I definitely don't want to sound sexist here but to me, men and women differ greatly when it comes to the question of "what constitutes as cheating?". Of course some exceptions are made but in general, their viewpoints will always differ. Hey, it's a Venus-Mars thing.
One cannot deny that during the course of a marriage, there could be some individuals (other than your spouse) that seem sexually attractive or pleasing to the eye. And no, there is no harm in people-watching or even admiring their looks. I would go as far as that. And beyond that, I call it cheating. Yes, I am THAT traditional.
The problem with cheating happens when a husband-wife team have differing definitions of cheating. For instance the husband goes out for breakfasts / lunches with lady friends. Even friends of the wife for example, without telling the wife. If it was a harmless meal, what's the harm in telling "Hey, I'm going to have lunch with your friend today". Why make it discreet? And sometimes they go as far as telling the friend, "Please make it discreet, don't tell my wife"
Now for the husband, it's ok because no one knows. And for the wife, it's betrayal, because the husband didn't tell her. And why the need for a one-on-one lunch with her friend? But get this, the silliest thing is that.... you asked out a friend of your wife??? Kau rasa kawan tu tak cakap ke ngan bini kau? Or maybe it's just the thrill of getting caught. We will never know.
And especially for the husband, it is NOT cheating because no physical intimacy took place. And that is where we differ boys and girls.
And some engage in online sex or even sex-ting (oh the advents of technology!) and still claim innocence as there was no penetration involved! Amazing! Talk about bending the rules!
Bottomline is, whatever it is that you did to betray the trust of your wife is a form of betrayal, and betrayal is cheating.
But the sad part of this all is that once you've done it, the bond will never be the same again. Yes, your wife might forgive you and all, but no, it will NEVER, ever be the same.