Thoughts on Jealousy

So I M(28) and my girlfriend F(31) have been together for over 5 months and we really enjoy each others company. She attends a church where she lives and has a good friend who is male. The told me the reason she is friends with him is because they are both the only Chinese. She also mentioned she thinks he is very feminine and also thought he was gay. He is not by the way. I couldn’t help feel a little jealousy when she brings him up in conversation because they attend church events together. I know she doesn’t hangout with him outside of church. How do I go about this. I don’t want to be insecure and tell her not to hangout with him. I do not want to control her life. I just want to know if it would be a good idea to mention how I feel to her.