I think it depends on the person but personally I wouldn't say it mattered. Some people however take anniversaries and remembrances very seriously though.....
Mainly I have trouble remembering stuff anyway unless it's something I'm real into like music or my personal obsessions. Relationships are very hard and what's worse, I'm terrible at names. I've had some people misconstrue it to mean that I didn't care or was being rude on purpose. Usually it was the opposite, I'd sit and struggle with remembering which I think is part of my executive dysfunction. So sometimes I think anniversaries and social functions are more or less subjective to each person. But traditionally we're usually taught and raised in the importance of anniversaries, birthdays, and anything to do with interpersonal relationships and the significance they each hold.
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I live as I choose or I will not live at all.
~Delores O’Riordan