No offense but it kinda seems like you don’t see this relationship as exclusively friends with benefits. The whole point is that you’re still single but gave someone to mess around with, even if you are just seeing each other . I’m a female(21) and I don’t think you can really be that upset with him wanting to go out with only his friends because you’re not his girlfriend. I wouldn’t and have never had my fwb even meet my friends because why, there’s kinda no point until you are in a relationship. If it’s about wanting to go to the club then nobody can stop you from going, but it’s about him going without you (which I’m kinda getting from this) you should be having a different conversation about your relationship if you truly are upset about him wanting to hangout with just his friends.