Is porn cheating?

I don't think it is, however, earlier this weekend I ran across a post about someone else who thought so. I believe it's childish to think it is, because a male body needs that release. I feel like most females don't understand that, we don't have a thing between our legs that can become present. Another thing, if you are watching a R rated movie, and... I don't know... Margot Robbie comes on the screen naked, do you cover your man's eyes because he is seeing another naked woman; therefore, he's cheating (sorry for the run on sentence)? God forbid him to watch "Game of thrones". Personally, I believe a guy watching porn is like a girl watching a chick flick or reading a romance novel. I dont mean to backlash anyone who believes porn is a form of adultary (even though the word means having intercourse with someone that is not your spouse, and masturbation is not a form of intercourse), i just want too understand why you think it's so bad.