I agree with jfrancis here, cheating is breaking the rules of a relationship behind your partner's back, no matter what those rules are. If a rule in your relationship is that you don't shower on Sundays, and you secretly shower on a Sunday while your partner's still asleep, then you're cheating. If in your relationship it's ok to have sex with your partner's best friend (or to watch porn), then if you have sex with your partner's best friend (or watch porn), you're not cheating.
I guess problems occur when the rules are unspoken and not congruent with how the people involved really feel about it.
Squid's post reminded me of one of my past experiences so much! Several years ago I had a boyfriend who used to watch porn regularly, and I definitely had a problem with it.
At that time I didn't really like my body and my boyfriend often criticized it harshly, too. I knew he found me too fat, too white, etc. In those porn movies he was watching on the other hand, most women had nearly perfect bodies. Most of them were very young, they were thin, pretty, with perfect breasts, etc. I thought he found them way more attractive than me. I definitely saw porn as a concurrence, and there was just no way I could rival them.
Plus those movies were obviously made for men to identify with, mostly showing the girls. Knowing that my boyfriend looked at them, got sexually aroused by them, masturbated and imagined he was having sex with them really felt like he was cheating on me. It hurt me a lot, in fact it made me sick of jealousy!
Another reason why I found it so unfair is that those movies were so unrealistic. I have no comprehensive knowledge of pornography, but from what I've seen, what happened in those movies would be quite boring for most women in real life. Those girls scream and act as if all this were totally great, when in fact they merely get f***ed. In real life, sex is a bit more complicated and women have higher demands. My boyfriend often got upset at me when he didn't succeed in satisfying me sexually, and what I thought then was "hell yeah, in those movies you watch it's a lot easier, huh?"
I think porn propagates a completely distorted image of sexuality, especially of female sexuality. It's like an unrealistic "made easy" version. Those girls also never have their period, they never have PMS, they have no emotional needs, they're always perfectly epilated and shaved, and so on. How can a real life girlfriend with an average body, with daily life stress and a sexuality that may appear complicated to an inexperienced guy keep up with that?
Sorry for going off-topic and for getting a bit emotional about that. Looks like it needed to get out!
