Two partings sit side by side here: one in the past, one in the present. The speaker remembers saying three words to a friend they were losing, after which neither of them could find anything more to say. The poem never tells us what the words were, and that silence is part of its point. Some endings leave nothing else to say. The speaker also admits the friendship was already slipping away, as if the two were meant to go separate ways from the start.
Tonight the speaker is on the road, again saying three words and again running out of language. They are heading toward something unfamiliar, thinking about what they left behind. The mood is quiet, sad, and a little weary, yet it ends in trust. The speaker believes the path was laid out by "someone or something" that knew what was best. Grief is still there, but it is softened by acceptance.