I had a boyfriend who kept a stack of playboys by the bed. He was a delightful, inventive, creative lover who treated me like a queen. I didn't mind the porn.
My ex husband had a secret, daily porn habit. He told me he was basically asexual, and that lie continued for about a year and a half (a frustrated, confused year and a half for me) until I found out about his online hobbies. I hit the roof about the porn.
It's all context. I think porn does more harm than good, yeah, it trains viewers to respond to things that aren't real and by contrast tune out things that are. But we're all wired differently, for every porn (and alcohol) addict there's another user who isn't compulsive about it.
I agree-- it doesn't matter if it's "normal" or not. To me, it's not normal to continually do something that hurts your partner, and "forsaking all others" doesn't mean "except when I want to look at naked, airbrushed pictures of others without my partner's knowledge." Personally, I'm a very tactile person, but while I was married I didn't think I had the right to touch other men for jollies.
It was a relief to say, "OK, maybe I'm overreacting, but this is how I feel." I eventually got a divorce from the porn addict and took up with a man who was neutral about porn, and into me, and that was a relief.