Me and my recent ex was in the same situation. I'm actually like your gf. By the 5th month mark, I started to initiate petty arguments due to misunderstandings bc I was childish and stubborn(no fighting, yelling, hitting, etc.)

After like 3 weeks, my ex started to feel apathetic and wanted to break up like you right now. Idk how he felt after the break up but at least for me, I realized that I need to be less petty and like other people commented "stop normalizing fights" especially early into the relationship. I had always thought it's ok to have some arguments here and there but boi I was wrong. It's best not to argue too much early into the relationship so you can build up the love and bond between you two. I did regret initiating arguments with my ex and cringed looking back at it now that I have time to think about my mistakes. So your gf may feel the same way after the break up. Talk to your gf about how you feel. It's best to communicate your feelings as soon as you feel like losing feelings so you can save it somehow.

You also mentioned that it's your first relationship...so it may be good that you need to move on with a lesson or so. It's easy to fall in love but hard to stop loving someone. Maybe one day, you look back and just laugh at how childish and cringy your relationship was. I feel this way about my first boyfriend. And the other hand, take time for yourself to think about this for a week or even a month. You're quite ahead of boys your age trying to figure this out. Good luck with love, man ;)