I've had a couple of ex's that were addicted to the point where they preferred porn over me. Even when they were with me they struggled to orgasm because of how desensitized they were.
I was strongly against it for a while after, but not so much now, as long as it's not a problem. I know my boyfriend watches it from time to time and it doesn't bother me because he doesn't let it affect our sex life.
I don't watch it and have never really been interested in it. It's the complete opposite of what I'm looking for when it comes to that sort of fulfillment.
Oh - and I do think while not all men watch it, most do.