If you have even seen a pack of Tarot cards, you’ll find that the card of Death represents change. So Death = change. That is a truth whether you believe in tarot or not. Death = Change.
More so in death than any other loss is what I call the ‘year of firsts’. The first birthday(s), Christmas, and so on until it ends on the anniversary of their death. Their absence is more acute on these days. It is the beginning of the course to finding the new normal. Doesn’t mean all the grief goes away, but it is all a part of the adjusting to the change.