You can't fix it. Sounds like this person you're with doesn't want to seriously commit to a relationship with you, so is knit-picking and starting fights so that you will break up with them. Men do this all the time.

I mean, you could call this person out, tell them, you notice that they are saying things intentionally to start fights to distance themselves so you'd like to know why they are doing it (you already know why though). See if they are honest with you. They may keep deflecting because they are weak minded, so be prepared to go in circles and get nowhere if this person is emotionally immature (which it sounds like they are, if they are starting fights for no reason).