I need yall advice M21 F19

Me and my girlfriend have been having random issues when she when to visit family and friends. Im an anxious attachment and this group has helped me before on understanding some issues in my self.

Now for what happened, her and her brothers had an agreement and I told her if she needs to talk im here, she said maybe later, she doesn't want to right now and I understood a reassured her im here if you need it. A few minutes pass and her friend picks her up because she was staying over and later she said she already talked with her friend. That felt like a kick to the chest because she couldn't tell me but told her friend right away and I don't fully understand why it hurt so bad. I do know in the past I've felt distant because she wouldn't share emotions with me and that's one of the ways I feel connection or intimacy. She has worked on that and I always thought she was just not the person to share but she was able to share so easily with her friend but not me.

I know I have my issues and need to work on them but I need to understand where they are coming from and I hope you guys can help