How do i get my boyfriend to stop watching ?

I have been with my boyfriend for 2 years and we have lived together for the last year. We are truly in love and each others halfs and going to marry one day. He is a great guy, the best ever for me, except the fact that I keep finding sites on the computer . most of the time he completely clears his history, but sometimes he leaves off sites. Yesterday I caught him looking at a naked actress from the movie we were watching. I was sitting right there next to him. As soon as I go to the restroom or in the other room, he looks at ographic sites and naked pictures. Imagine when I am not home :) He also looks at other girls while I am outside with him at the store or anywhere else on every corner. Yesterday I told him I am fine with him looking at other girls and , but just not in front of me. I am right there and it is disrespectful!!! I told him it is not fun for me watching him watch other girls. He said he has to watch guys check me out too all the time. But he said he will try to be more respectful from now on. Why is he doing that? Everyone thinks I look gorgeous and we have a great life...every day. I felt like if I told him to stop watching , he would lie to me and watch it even more. I know he will never stop watching it. I don't hold any illusions. That's why I just told him to have the respect not to do it in front of me and if he looks at girls in public in front of me to do it briefly not twisting his neck and rolling his eyes and all those maneuvers. Do you think that would be effective?