All I know from my own experience is that the more loss we feel the more grateful we should be for whatever it was we had to lose. It means that we had something worth grieving for. The ones I'm sorry for are the ones that go through life not knowing what grief is.
I know for certain that we never lose the people we love, even to death. They continue to participate in every act, thought and decision we make. Their love leaves an indelible imprint in our memories. We find comfort in knowing that our lives have been enriched by having shared their love.
Wabi sabi acknowledges three things: "nothing is perfect, nothing lasts, and nothing is finished." So, at first glance, it seems to celebrate the very thing that causes suffering. Yet, Basho found that wabi sabi led to enlightenment. So what is going on here? Basho himself studied Zen for several years and traveled in disguise as a Zen priest, yet he clearly became attached to people and places, wept openly beside ancient battlegrounds and other sites of romance or valor. He suffered gladly the pains of attachment and sympathy, identified with nature and its pathos. Either he was not very disciplined in his Buddhist practice, or he understood something about attachment and loss that we could do well to learn.