Overprotective boyfriend?

Okay so I recently turned 21 earlier this month and only one out of my close group of friends is 21, the rest of them along with my boyfriend will be this summer. I want to go out to bars but I don’t really have anyone to go with because my one friend likes to drink at home. So I posted on Instagram that I’m in need of a bar buddy and an acquaintance of mine hit me up and said he’ll take me out and buy my drinks since it would be my first time going to a bar. I told my boyfriend about it and he immediately shot the idea down because he thinks the guy will try to pull something and make me end up cheating. do I have the right to be mad? should I go anyway?