My dad keeps venting his anger about his girlfriend ignoring him on me. What should I do?

My dad has a girlfriend whose daughter is truant (won’t go to school). The girlfriend has had to take her to court and things like that and lately she keeps ignoring my dad. My dad didn’t know what to do and after about a week or so of not hearing from her, he broke up with her. The whole time she didn’t talk to him, he was getting madder and madder. He has a short temper already but it seemed as if he always puts me in his line of fire. He and his girlfriend got back together but he says she has started ignoring him again. I’m already on a short fuse. What should I do to get him off my back?