This happens because she is your girlfriend and you love her so much. And she is protective of you for the exact same reason.
She is a fair fighter. Every couple has arguments sometimes, and there are no people who are perfect. And of course, you need to have at least one misunderstanding to see if you are really compatible, and to check what your girlfriend is like during the disagreements.
If she does not get too heated up or angry and does not bring up your personal issues that you told her about just to hurt you, then she is a mature person who is used to resolving conflicts as an adult. This is an indicator that she loves you too much to descend to low blows and exchanging unpleasant hits.