Hello, I'd like to help you with your question. It sounds like your girlfriend feels she needs support during your arguments, someone to agree with her and make her feel she is right. But by calling her friend in the middle of your arguments, she breaks the trust you have between you. And trust is a basic need in a relationship. Without it, the relationship breaks down. Your reaction to what your girlfriend does is not wrong. By breaking your trust, your girlfriend takes away your ability to work your deeper feelings out during the argument. When you have someone "reporting" your thoughts and feelings to someone outside of the situation, it is normal to shut down and not want to share anymore with her. Your behavior is not controlling, it is protective. And it is your right to not have your personal arguments told to other people. And your girlfriend is not recognizing her role in making you shut down. Instead, she is blaming you for not continuing in this destructive pattern that helps her feel better and hurts you. To help the situation, try talking to your girlfriend when you are both not upset. Let her know that you find her behavior hurtful and that you consider your arguments (and any other aspect of your relationship) private and you would appreciate her not sharing what happens between you. Also, let her know that your trust of her is lower when she does these things. If she won't work with you however, you may have to avoid arguments with her and just walk away when you get upset. You could also ask her to talk to a counselor with you. Sometimes it only takes a session or two to work things out. She needs to hear from someone outside of your relationship that what she is doing is hurtful and causes you to mistrust her.
I hope this has helped you,
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