Are my feelings valid?

My boyfriend (20) and I (22) are long distance. He is about to go see some friends he hasn’t seen in a while and they plan on going to the club, the friends he is going with are all single. This hasn’t been the first time he’s gone to one but every time he goes, I just feel terrible cause I’ve always not like the thought of people in relationships going to clubs with their single friends because they would obviously want to to single things. I’ve told me him multiple times how it makes me feel but he just says that he wants to have some fun with the boys which just makes me feel like my feelings aren’t valid or that I’m not being heard. What do you guys think about my situation?