Is it okay for my boyfriend to look at other women in front of me?

My boyfriend "Mike" and I have been together for almost three years now. During these three years there have been several incidents of him looking at other women whenever we go out to clubs. I understand that men are visually stimulated and that when they see a beautiful woman, they are going to look, however, I just wish Mike wouldn't look at other women when I am around. He doesn't even look just once; whenever we go out, he continuously will look at a woman that he thinks is attractive all night. I have confronted him about this several times now. These confrontations usually begin with him denying that he was looking at other women and end with him promising to stop (he has yet to fulfill this promise). As a person, I am feverishly insecure. Although I get perpetual affirmations from friends, family, and sometimes even strangers telling me how attractive I am, I still feel so insecure about my looks and intelligence. My boyfriend's wandering eye certainly doesn't help. What to do?