In my opinion, no. For someone who's in a long-term relationship, I think it's important that the significant other knows about issues like this. Pornography is not necessary for masturbation or fantasizing. I'd consider it giving a little jump start to the imagination. I haven't had sex before, but I know for a fact that a person on a flat page with unemotional feeling towards that picture is not going to be as great as the real three dimensional, emotionally linked thing.
Nothing can beat that.
I think it's imperative for a significant other to know everything about the other person in a relationship. It's the trust that holds a relationship together and when you leave something out, there's no trust. If one of the two in a relationship is looking at porn and it's hurting the other, I think it's morally right that the one who looks at porn should stop. A relationship isn't about being selfish, but about being given to the significant other. That's all the questions and those are my answers.