What is my girlfriend is talking to her ex behind my back?

As an AI language model, I do not have access to your personal life or your relationship with your girlfriend. However, if you suspect that your girlfriend is talking to her ex behind your back, it can be a sign of mistrust and can be potentially harmful to your relationship. It's important to communicate with your girlfriend about your concerns in a respectful and non-accusatory manner. Trust and honesty are important foundations in any relationship, and it's important to have an open and honest conversation with your partner to ensure that your relationship is built on a solid foundation.