What's His Deal?

My dad has always had a temper. Ever since I could remember he rarely came with my mom, sister, and me to family events when it comes to my mom's side. He always used work as an excuse since he does work at night when we usually stuff. But when it's his day off he will say he doesn't have a life and would rather just stay home. It seems like he's just getting worse as the years go by. I have no idea what's his deal. It's like he's depressed or something. It worries me sometimes because he'll just push my mom farther and I'll just get more irritated with him. Hopefully he'll wake up and realize that by isolating himself from these events, he'll just isolate himself from us. But I doubt he'll change. As people grow older, the harder it is for them to change.