I related to many parts of this; losing touch with things or ideas you connected with your person can feel like a new grief yet.
In a larger sense, one’s place and perspective in the world or the universe has been permanently displaced, and one is left trying to make sense of an absurd existence littered with traces of the one you love.
I’m used to the world without him now but I feel the same irrational frustration as the author seeing people the age he would be now and thinking “why did you get to live and he didn’t?” There are so many things I would like for him to have seen, things that he wanted for me that came true.
It’s strange how some of the grief never leaves and pops up unexpected. I got all teary watching Field of Dreams after probably 25 years...a fun movie when I was a kid but as a grown up the tension between fathers and sons.
If you did not see "Big Fish" when it came out in 2003, I highly recommend it as it is one of the best movies that I have seen that explores the relationship between a father and son.
https://m.youtube.com/watch?v=rziFIdDjfHo
https://m.imdb.com/title/tt000319061/
EDIT: On second thought. This movie might be a bit too heavy/close to home for you or others who have lost their father to watch, but the recommendation still stands for others.