McDonalds is going to get the job done, but it would NEVER EVER replace a good steak dinner. Porn and sex with you are comparable to McDonalds or a nice steak dinner. As long as your sex life if normal and he's not viewing porn as a replacement for being intimate with you then it's not really a big deal. Men are very visual creatures, so when they get that urge to masturbate, they want to see something visually appealing.
He is not comparing you to porn women, he is not comparing your sex to porn sex. It does not have anything to do with you. I will make a few points here that I've learned: He's been watching porn probably since he was about 12, much longer than you've been around for sure.
