Hi Rachael,
I think that arttitudes to pornography are one of the biggest gulfs between the sexes.
Some women feel that a man should be content in a relationship, and only want his partner, and not 'need' external stimulation.
Some men feel that viewing pornography is harmless - and a lot of women agree, but it does come down to personal circumstances.
I think it is only courtesy to keep viewing habbits private - I might look at a pretty girl walking down the stret with my wife, but that's not the same as going Phhoowarrgghh, look at the a*se on that!". It's a matter of consideration.
I do believe that men will always look at erotica, because their sense of visual stimulation is easily stimulated. It's not a case of 'preferring' pornography to a partner, it is simply a matter of private indulgence, and really should not normally affect a relationship, or intimate feelings in 'real life'.
Where the problem arises is if a man watches exessive amounts, knowing his partner is upset, but continues - but that is the same as if he eats himself four stone overweight, knowing that his partner is worried for his health - it's about caring for someone and being sensitive to their attitudes.
Your partner should be far mor discreet in his viewing, and not be bookmarking on a shared PC - I hope you get this resolved, but if you are still not happy, then that is the isue, not what is making you unhappy, and that needs to be resolved so you can move on and be happy together.