You know I started thinking about this more and maybe its just me, but it seems that's the age you question friendships.
I.e. when I was 23/24, my friends had pretty much finished college before I did (too many major switches) and once I graduated at 24, it was after 9/11, the economy was going downhill here and most of my friends packed up and moved out of state. I remember at one point my only remaining friend was talking about moving and it turned out she was talking future, not immediate, but in anycase though I actually begged her not to move!
And yes, even if its 2 years after a breakup and you're with someone new, you're still allowed to question what's going on in your life. It's a way to assess whether or not you're on the path you want to be on. The thing that sucks though is that somethings the check happens with a lot of tears.