Whose heart's sorrow is this sky, a flame rises from this morning.

This beautiful couplet speaks to the overwhelming, almost cosmic nature of passionate love. The poet suggests that the passion burning in the sky itself is intense. It's not a sudden burst, but rather a gradual, inevitable rising, much like the first flame of dawn. It beautifully equates the intensity of emotional longing to a natural, unstoppable phenomenon. It implies that some feelings are simply meant to be, rising organically from the depths of the heart.