I'm attracted to other girls, but I guess this could go for anyone:
I don't see a problem with a person in a relationship looking at porn.
It's like you're married to a comedian. Would that comedian say you couldn't watch other funny people performing? I doubt it.
That was probably a terrible analogy, but that's my opinion on this.
I am homosexual. A lesbian, actually. If you have a problem with that, then it sucks for you. It's not your problem. It's not even a problem. I quite like it this way.