So and girl best friend

Ok so I need opinions... Am I Being crazy?

My boyfriends best friend is a girl he works with. He is always going out on lunch breaks and coffee runs with her. He tries to hide it from me but I have found out a couple times. They always text each other as well.

He says he loves me and we are trying for a kid and live together but I still get super self conscious about it.

Is it bad that I feel that way? I've met her a couple times and she seems nice. She seems like more his type than me so that makes it worse.

😕😕