In other words, if you are / were in a monogamous relationship and your honey started getting it on with someone else, at which point would you say that they had begun cheating on you as far as you're concerned? What are you okay with? Where do you draw the line? First they hold each other for a minute or two. Then they begin french kissing. Then they begin fondling each other through their clothing as they kiss. Then they start taking their clothing off as they continue kissing. Then they begin kissing each others neck and chest area. Then they begin masturbating each other. Then they give each other oral sex. And then they fuck.

I realize that there's great variety to physical intimacy, this is just something of a general step-by-step example to go by. Also, let's try and keep this as a serious discussion so that the thread isn't closed.