I think its simply desensitization. Sex has less of a hold on you when you are less horny.

When you see porn and compare even "vanilla porn" one man, one woman, and compare it to your own marriage, you may find it lacking.

There is a fine line between "unrealistic" expectations and realistic ones. I find a lot of women who blame porn for problems in their marriage do not put a lot of effort in the bedroom side or maintaining their own looks.

If you don't want your man looking at porn, give him something to look at.