Is it normal to have a social partner?

The question is more...what do you do with a really social partner? What if it looks like they are flirting with someone else right in front of your face but you know inside that he is being social BUT the other person doesn't know that? I feel insecure even though I know my bf is really social and likes to talk to people. I like that and I like giving him that freedom. I'm also the same way except, I kind of lower it down when he's there just for respect or to leave out any confusion. But for him, especially as a guy, he doesn't think of that and basically acts single when we're with friends. I'm fine but when it comes to the other people, they might look at me like I'm being ignored or as if he is flirting with them. It gets annoying and I feel like I have to verbally show that he is just a social person and not flirting. I don't want to feel like I have to do that but it leaves me no choice. So whats the best thing to do in this circumstance?