Flirty Fiancé (long story)

As

My fiancé makes me the happiest I've ever been and is the best partner for me. He's a very smooth talker tho I tell him he can sell fire in hell or water to a well all the time 😂 so females always like talking to him and he's is really friendly so he usually makes small talk. My problem is it doesn't end there, he exchanges numbers or social media and then holds conversations there. He claims they are his friends but I feel a little weird about these friends. And why can't it just be small talk and that's the end of it. He says I'm way to smart pretty and sexy to be this insecure. I don't think it's insecurity though I think it's a respect thing. So l accepted a friend request on Facebook from a guy and he called me thru messenger while we were together so I didn't answer now he's mad at me for the same thing that he does. Isn't that a double standard? Am I wrong? What should I do