It's a lot easier to not notice that you're getting older if you don't hang out with the same group of people (periodically) over time. The problem with infrequent get-togethers, is that it's a stark reminder that your friends are all getting old (and, by extension, that you're getting old).
Used to only notice this when I would go home to visit my parents. Each time I did so, they looked older - particularly my father. It got to the point where the visible aging became hard to bear and made it such that, even though I really loved my parents, I couldn't bear the psychological toll of seeing how much older they looked each time I saw them. It meant that visits became more and more infrequent. Sadly, with reduced frequency of exposure, the progressive effects of aging would be all that much more apparent because the snapshots had longer intervals between them.
Who knows: maybe the key to not being bothered by it is to see people more frequently That way the changes are less stark and the resultant shocks less jarring.
Dunno, but people need to stop getting older - it makes me feel too old when I see.