What is is it ok for girlfriend to hit me?

It is not okay for anyone, including your girlfriend, to hit you. Physical violence in a relationship is never acceptable and is a form of abuse. It can lead to serious physical and emotional harm, and it is important to seek help and support if you are experiencing it. It is important to remember that you do not deserve to be treated this way and that there are resources available to help you leave an abusive relationship and heal from the trauma.