Perhaps someone's heart was wounded in that alleyway; my heart's mirror shattered beside me.

This profound couplet speaks to the fragility of the human heart. The poet suggests that perhaps the beloved (Kaso) was hurt by some external event—a street or a moment. But the real devastation, the shattering of the 'mirror heart' (sheesha-e-dil), happened right in the presence of the speaker. It’s a powerful realization that sometimes, the most delicate damage is done by the closest proximity.