Boyfriend and strip Club

Jessie
So my boyfriend and all of his friends want to go to the strip club. The girls that they are sleeping with said that they will go with them.  It's my boyfriends friends and  their fuck buddy's that would be going. I told my boyfriend I would go if he didn't go. I don't want him seeing other naked girls. It makes me uncomfortable . Even though he told me he would never think about cheating,  or doing anything and he wants to marry me. I just don't want him to see other girls naked. But he hasn't been to a strip club yet and he says he wants to go once with me and his friends but I don't feel comfortable with him seeing other naked girls , it makes me feel more insecure than I already am.  He said he only wants to go once and that's it. Is it normal for a guy to go to a strip club  even though he has a girlfriend?