I think different people remember different dates for different reasons. I’d never forget my anniversary. But, I can only get to the month and year of my college or grad school graduations. And, you could hold a gun to my head and I can’t tell you the year my father died.
I love celebrating. So I get yearly reminders of bdays and anniversaries. I’m glad to have my degrees but who cares when commencement was??? The date does nothing for me. So while I cherish the culminating event in some tiny way, the “owning” of the degrees is more important than the dates. And, I was a Daddy’s girl. I don’t ever like to think of him being gone. So, my brain refuses remember the date.
I also find it fascinating how different cultures treat holidays and life moments. I have a friend who’s father is gone. He’sl buried in his birth state which is 8 hours by car from her. Twice a year on her father’s birthday and Memorial Day, her mom along with the kids and their spouses all drive down to visit the grave, stay literally just one night to rest and drive back. In contrast, I’ve never visited my father’s grave (and he wouldn’t have wanted me to) and I lived in the same city as it’s location on and off for 15 years ish
Or, to get away from the morbid, some people really go all out to celebrate milestones like kindergarten graduation. I can’t think of much that felt like more of a waste of time when my kids were little. I like to celebrate and throw a party but, Kg graduation??? My kids’ school even put them in caps and gowns that were as pricy as college versions.
I was the only mom bewildered as to why this mattered. 
Everyone else was crying like their kids were going off to war. 
Now....college graduations? I acted like a complete kooky joy filled idiot. But, kindergarten and grade school graduations ? C’mon.
