It is a good one. I can't claim to have originated it. I heard some other wise person use it in a similar context. It is true, though, not mere sarcasm. It is with love and well wishes that we should part ways with people. Because we know sometimes it's the way it has to be.
A sage once said that the people you met in life, as well as the duration of association, is all predetermined and therefore don't regret when the association comes to an end.
I really appreciate your point of view on this b. i can relate your comments to a relationship i had with a dear friend not so long ago and the circumstances surrounding us. While i do not disagree with some or your points.... i believe i finally hooked onto an understanding of the main purpose of the relationship- that is that there was a gravity and seriousness about it that exceeded any balance that could have manifested common ground and reconciliation as friends. Notice i am not blaming my friend but rather i am talking about an energy field that manifested surrounding us that was a carry over from previous incarnation events. In this sense this tread does not coincide with what your post triggered because it is about the very opposite: friends that never have returned. We can easly look back and see how people-including us- have taken ourselves and circumstances far too seriously.