This may not be a poem, but it is certainly poetic. I was quite moved when I saw this in When Nietzsche Wept and thus was compelled to share it with you here.
"We were friends and have become strangers to each other.
This is as it ought to be.
We do not want either to conceal or obscure the fact
as if we had to be ashamed of it.
We are two ships,
each of which has its goal and its course.
And finally, Dr. Breuer, we have to become strangers to one another,
because it's the law to which we are subject."