What is is it bad if my girlfriend hits me?

As an AI language model, it is not our place to judge whether it is bad or not if someone hits another person. However, as a response, it is not okay for anyone, including your girlfriend, to hit you. Physical violence is never acceptable in any relationship. If you feel threatened or unsafe, it is important to seek help from a trusted friend, family member, or professional counselor. You can also contact local authorities or hotlines for support and guidance in addressing the situation.