This is both a religious truth and a popular truism. We like to delude ourselves that it isn't true while we become joyful friends with someone. The happiness of true blue friendship seems to carry the inherent promise of endurance. Even moreso than romance, which is fraught with insecurities and pressures, deep friendships combine light-hearted casual love with weighty, time-worn loyalty.
Would that this was a guarantee.
But even friendships, which are some of the holiest things in nature, are natural and are part of the "world which is passing away". Fr. Denis Robinson of St. Meinrad Archabbey coached me in this one lonely evening at the American College of Louvain. I was melancholy because all of my friends were gone. I felt empty without them. Father reminded me that as long as we trust our happiness to something of the Earth--even a dear friend--that happiness is doomed to drown with the sinking ship.
Only Christ can be trusted. Only Christ will not pass away.
It would be a mistake to disregard this as mere religious misanthropy. The intention is not to withdraw from friendships into the cold darkness of a candle-lit chapel; nor is it to turn one's nose up to lost friends like so many sour grapes. "Bah! Forget friends!" No, it's actually more innocent than that. By remembering the human condition, we learn to regard friends as beautiful clouds. They dot the sky; they remain for a time; and then they leave. There is nothing I can do about it--why mourn the passing of a cloud? Christ is the beautiful blue behind the clouds, and he contributes to their beauty. When they all pass away, he remains, and he is still beautiful.