I may have misread this, so please forgive me if I'm completely off base, is that you both have friends of the opposite sex and see them alone, but one of you (him) gets upset when the other (you) does this. Correct?
I've been in your shoes. My ex wife had many male friends while we were together. She would see them once or twice a week and I was always fine with that. One of them was even an ex-boyfriend she had seen just prior to meeting me. I, on the other hand, was not allowed to see my female friends (even married ones who's husbands were there) without a fight. Being the stubborn guy I am, I let her scream and scream and scream...
In the end, one of those guys she didn't see anything wrong with seeing got her all sorts of knocked up... If he's acting like I assume he's acting, it's because he's trying to keep the focus on you so you don't notice him. I could easily be wrong, but even if I am, he's using a double standard and that's not playing fair. Don't waste your time with this boy.