Some amount of possession or jealousy is a by-product of love but this sound as an overreaction. Although many women are very sensitive about men’s habit of looking at pornographic materials but at the same time they need to accept that this is normal desire amongst men. If you are habituated to look at those sites or started neglecting her because of this then she should react. Otherwise she should leave this topic with a note that she doesn’t like you to see these sites. Make her read this answer, probably she will understand.
And by the way, there is nothing you should learn from pornographic site. It’s all about earning money while playing with your fantasies and stimulating you.