It would have helped if you told how old you guys are...
This is a very common problem most of the girls have to deal with....
Well, it's not like he's cheating on you with another woman...but in some people's books it may not be so..
Anyway, as a female you have to understand that the male pattern of thinking is completely different to ours. It is al most a part of their growing up process to watch a bit of porn. I know it is not considered moral...but you've got to let them realize it on their own.
In their teenage years they are fascinated by it & are almost obsessed with porn. Then they watch it if they get hold of good stuff(interesting stuff)..Then they usually get tired of it as they mature & they're more interested in the real thing!;)
It is natural for you to get offended & feel a little jealous. But try to reason things out....see, him admiring those busty women is like us girls drooling over George Clooney, Bradd Pitt or any other hunky celebrity. That doesn't mean you'd wanna leave YOUR man for a fantasy, right? Why? Because you love your boyfriend for who he is...
It is the same thing with the guys....I know it is easier said than done..but you have to understand this bit & it'll definitely improve your relationship.
It's ok for a guy to watch porn on & off....It only becomes a problem if he is ONLY aroused by porn & not by the real thing with you....or sometimes there are people who get addicted porn.
Just give the man his privacy. We all need our space some of the time.
But just let him know how you feel about it. That doesn't mean you should scream at him & pull another fight.
Just talk to him & also try to look at it from his point of view as well.
Take it easy.