"Tonight I Can Write" shows both love and acceptance of reality both through metaphor and explicit exposition. The narrator shows how he has lost his love, and that while he is trying to forget their love because of the pain it causes him, it might not be possible to actually put the love and the loss out of his mind. He continually compares both his own love and the nameless lover to the "endless sky" and the stars, showing how in the heat of the moment he felt their love could continue forever. Now, however, he knows that she will "be another's," regardless of his own feelings. In the last lines, the narrator seems to come to some sort of closure:
I no longer love her, that’s certain, but maybe I love her.
Love is so short, forgetting is so long.
Because through nights like this one I held her in my arms
my soul is not satisfied that it has lost her.
Though this be the last pain that she makes me suffer
and these the last verses that I write for her.
(Neruda, "Tonight I Can Write," eNotes eText)
The two important lines here are "Love is so short, forgetting is so long," and "this be the last pain that she makes me suffer." The first shows how the narrator is conscious that their love was a single thing in the vast world, and that despite this knowledge, the forgetting of his love takes much longer. The second shows that he wants to forget their love so he will not be in pain; he unconsciously blames her for causing the pain and decides that he will stop brooding on it and tormenting himself.