Believe it or not, lilstar, one's head seems to just plain get tired of dealing with the futility of these awful, awful injustices through time. It's probably that mourning thing, partly, plus there's just nothing one can productively DO with all 'that' so it feels like ( to me ) your head kind of gives up the pain. It'll never be ok, knowing he's out, your father is gone and you missed so much but when the head figures out, like it tends to do almost behind our backs sometimes, that we have no recourse to accept this ( but bear constant pain ) , it'll just stop feeling tooooo much, that's all. If you have a T, perhaps they can help you find some way to process things more quickly.
Peace to you.
Peace to you.