Themes
Tonight I can write the saddest lines. I loved her, and sometimes she loved me too.
— Pablo Neruda · Tonight I Can Write

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
Sorrow is the raw material here. The speaker says tonight brings the saddest lines, then admits the love was only sometimes returned. That small word 'sometimes' carries the quiet ache of an uneven, unresolved affection.
Context reviewed