She tells her friends about our pvt lives!

My girlfriend has a very annoying habit of discussing our private lives with her group of friends. I know she does it and I have asked her repeatedly not to tell them everything, but there is no way of me knowing if she does or doesn’t anymore because she meets them on her own. They have been very close since childhood and I love that they have this bond, but she changes her behaviour towards me and makes decisions based upon advice she gets from them, which is a huge problem for me. I don’t know how to change this because I don’t have any say in her friendships. It is starting to make me withhold information about my personal life because I know she will simply tell them everything. How can I change this?
Try and understand how this is affecting your relationship, and why. There is no way of knowing how or what are they saying to your girlfriend, so much of this is conjecture. We are all shaped by the opinions of our peers, so the big problem here is probably your anger about personal information being shared with people you don’t know well. If she can’t keep this information to herself, you are right to call her out on it and limit what you tell her. She should know, however, that this affects trust and communication between the two of you, which will ultimately be detrimental to your relationship. It is sometimes important to compartmentalize bonds with friends and loved ones, which she isn’t acknowledging yet. Give her time and tell her why this can be bad for your future with her, so she starts to look at it from your perspective a little more clearly.

Should I tell my girlfriend that a career move she is making is bad for her? She will think of it as me trying to control her life.
As an adult, she is entitled to make her own decisions and learn some life lessons on her own.