Flirting or Cheating?

If it's something your partner would not like you doing, I'd say that's cheating.

Ask yourself, "If my girlfriend was here, would I be behaving differently?" If the answer is a BIG yes, then you probably shouldn't be doing what you're doing.

I say it has to do with intent. Flirting in and of itself isn't cheating but it can be a precursor for cheating. Also you have to think about your intent. If the girl opened her legs to you and said take me, and you would, then the flirting you are doing will lead to you cheating.

Be careful because it isn't all about the physical either. Emotional cheating is worse because that means your heart and thoughts tied to that new person. That can hurt even worse.

Good luck!

Flirting becomes cheating whenever you cross that emotional or mental border in your mind. Intentional or not if your flirting with someone and they become someone you think about instead of the person your with or while your with your girlfriend/boyfriend/spouse then it's cheating. Sometimes even if you think you have just a "friendship" with someone a girl will see it as cheating if your telling her details about your relationship or intimate details about your life. Also if you cross any physical borders that's obviously cheating.

I would say when you start kissing her or something more physical. I don't think I would consider playful flirting as cheating. Though you probably should just stay away from other girls if you're in a relationship. Otherwise, you might come off as a player and your girlfriend may question your loyalty.

That's a really subjective question. IMO flirting itself isn't bad. It's when they act on it that they cross the line.