Am I being insecure or do I have a reason to be uncomfortable?

Myself and my fiancé have been together for 5 years, we have a mutual friend who introduced us and when we eventually got together we became closer with her. We have been friends for a long time and I have always seen her as my best friend- recently my fiancé has been getting a lot closer to her. She seems to have a lot more respect for him and I no longer feel like I’m really included in the friendship. It sounds stupid but I feel like my fiancé has taken my friend away and that he enjoys talking to her more than he enjoys talking to me- I feel completely excluded and it makes me uncomfortable. I have expressed this to him and he has just said that he doesn’t know what to say- I just want to know if I am just being insecure for no reason or whether I have a right to feel a bit uncomfortable.