Fight for her. Show her that you’re afraid to lose her. It doesn’t matter how long you’ve been together and how sure you are that you guys won’t end. You still have to show that you wouldn’t want to lose her. Just by showing her that reassures her that you haven’t lost any feelings for her. When you guys have a fight, she wants to see you stand up for your relationship when it’s on the brink of falling apart. She wants to see you tell her “No, I don’t want to break up” when she says “Maybe we should just end it”. She wants to see you give her a good reason to stay with you when she has a better reason to leave you. If you feel like you’re about to lose her, prove to her that you still deserve her and win her back. A girl just needs to see for herself how much you cherish what you share with her and you’d do anything to hold on to your relationship because it means everything to you.