I read this this morning and it sounds like a shit state of affairs, but I've been reflecting on it.
Your dad's mood is understandably low, he is possibly even suffering from depression. In these situations we tend to turn inwards, not thinking about communicating with others, even those we care about the most.
You obviously care deeply and love your father. I would suggest letting him know this and looking at getting extra support in if necessary (easier said than done).
We need to keep looking after each other. It's the only way forward.