This is a situation that has always bothered me too. What I always have to keep reminding myself is that men and women are completely different sexual creatures (most of the time!). A lot of women can go weeks without sex and/or masturbation and be okay with it. To have a guy go weeks without sex and/or masturbation has to be hell! Most men are visual and that is where porn comes in. I agree, it sucks to think that he is visually fantasizing about these women, but it probably means nothing more to him than an aid to get rid of the built up tension. I always dream of a perfect world where temptations don't overcome us, but that isn't the world we live in. Some people have addictions, temptations, etc. they spend a lifetime trying to battle and we each have our own faults. To make a relationship work, you have to find some sort of happy balance and understand that some things are going to happen that you or him may not be fond of, but have to try to gain some sort of understanding from the others perspective. Everyone has their tolerance point and if this is simply something you cannot compromise on and something he cannot change, then calling it quits is your next option. Personally, I'd rather have my significant other masturbate to porn than trying engage in something physical with another woman. Although, it would be crossing the line if he was engaging in webcam chats and something a bit more personal.