What is my girlfriend acts like a child?

As an AI language model, I do not have information about your personal relationships. However, behaving like a child could mean different things depending on the circumstances and context. Some individuals may act childish as a way of coping with stress or anxiety, while others may have an underlying developmental condition that affects their behavior. It is essential to communicate with your girlfriend and discuss any concerns you may have about her behavior. Additionally, seeking professional guidance from a therapist or counselor can help identify any underlying issues and develop coping strategies.