Strange relationships with his female friends or paranoia ?

I have been dating a man for a few months now. Everything is perfect so far, he’s been incredible with me. However, there is one thing we cannot agree on.

He has mostly female friends, which doesn’t bother me. He will see them alone, drink with them, I join them sometimes and all of that is fine. But a couple of his closest girl friends talk sexually with him. Their conversations are always very suggestive, sexual jokes about eachother, about each other’s bodies. Sexual comments on his Instagram.

I have already discussed this with him and we will never see eye to eye. He claims that they are so close he feels comfortable to make sexual jokes because he knows they don’t feel sexually attracted to him and vice versa. I am not the jealous type, I am not insecure and I don’t believe he will cheat, but I think it is crossing a boundary in purely platonic friendships and a little disrespectful to your partner.

I will never ask him to change this, his choices are his own, and I am also free to walk away.

Am I being paranoid and should try to drop this or am I right to see this as inappropriate?