Oh sister cuckoo, why do you, despite my pain, sing 'Too-oo Too-oo' in harmony with the monsoon's sound without me?

This couplet expresses a deep sense of personal sorrow and isolation. The speaker, feeling immense pain, addresses a cuckoo bird. They question why the cuckoo is singing its characteristic 'too-too' song and rising with the melodies of the monsoon clouds, even when the speaker is suffering so much. It's a poignant moment where the speaker feels disconnected from the joy of nature, wondering why life and its beautiful sounds continue without acknowledging their personal grief. The cuckoo's cheerful song, usually a symbol of love and monsoon, here highlights the speaker's profound loneliness and heartache.