Friendships, like so many other 'life' things, don't really have 'expiration' dates.
The word 'expiration' lends itself to the thought of curdled milk, a useless bus ticket, or some government issued labeling of a human death.
Perhaps what really happens, is transition. After-all, this seems to be the prevailing fact of life, to move from one situation, to the next. The real challenge about this fact is keeping it alive on your random adventures with your mates on some Tuesday. Kayaking, road-tripping', or beaching it up, you often don't take a moment to realize the true beauty of these special moments.
If we remember, even if only for a second, that our time together with those we love is a rather short, treasure filled ride of magic, it's meaning becomes so much more.
As friends come, and yes, go, from across-state moves, to falling-outs from character changes, all the way to 'good-byes' at funerals, the chapters we share are often brief, and only fully realized when our hairs have long turned grey.
From a scientific perspective, perhaps we were just two 'drug' (if one explores the definition of drug, one sees that we are basically comprised of drugs) filled chemical structures, organic in nature, exchanging information, probably about survival, or reproduction tips, grew, and then parted ways, rinse/repeat.
However, what the wanna-be hippy poet like myself chooses to believe, is that two souls, on a long journey through many different lives, have some how managed to cross paths again, help and nourish each other once more, and having realized all of this, never say goodbye, but rather, see you later.