It made me uncomfortable to begin with. Mostly because our sex life was the pits at the time. I felt like he was replacing me with much better looking women. I told him precisely that. He reassured me that even though he liked looking at those women he #1 knew they were all airbrushed-I was real, #2 couldn't actually have them-he could have me, and #3 he didn't love them-and he loved me. We actually started looking at it together. Partly because I was still curious to know why he was so interested in it. We began to share comments about it and it would get us both thinking sexy thoughts. We started going to the bedroom all turned on and even ended up right there on our home office floor. It put some spice in our lives. It was then we made our own little home movie and then erased it a little later to prevent it getting into the wrong hands. Also we started taking pics. It gave him still photos to look at of me and made me feel like an "equal" with these airbrushed women. I'm totally fine with him looking at pics now and he doesn't hide it from me. I think the hiding was one part that made me uncomfortable at first and that's gone now.
It's a craving that I think most men have. It's normal. It's also normal for us as female partners to be uncomfortable with the "perfect" image we see in porn possibly replacing us in our partners mind. Talking to him and reassuring yourself that he still sees you as sexy and wants you in reality more than those women will help you not fear him looking.
Personally I wouldn't tell him he can't look. Cause there's a real good chance that he will and if he doesn't he might resent you. Even if he's the one who announced that he wouldn't look.
Communicate with him about why it bothers you and ask him for reassurance. You might be pleasantly surprised with what he says.
BTW Some of the porn we were looking at in the beginning - Good Ol' TFP!!