Don’t know what to do

My boyfriend and I have been together for almost 6 months now..he is amazing! So good to me..but his friends which are much younger than him..messaged him and asked him to go with them to the strip club next week..and personally I’m not okay with this..before we had got together they would all constantly go to strip clubs and he stopped going once we started dating..anyways I’ve expressed that I don’t feel comfortable with him going and he says if I truly don’t want him to go then he won’t...but I feel like he is a big boy and can decide for himself what he’s going to do..I’m just pretty annoyed that it’s even crossing his mind to go..I’m not his parent so I feel weird telling him not to go so I don’t know what to do.