Even her boy, who had brought her, while she lived, her keenest sense of reality (and Browning's whole treatment of her motherhood, from the moment she knew she was in child, till the hour when the boy lay in her arms, is as true and tender as if his wife had filled his soul while he wrote), even her boy fades away into the dream.

It is true she was dying, and there is no dream so deep as dying.

Yet it was bold of Browning, and profoundly imagined by him, to make the child disappear, and to leave the woman at last alone with the thought and the spiritual passion of her union with Caponsacchi-- O lover of my life, O soldier saint, No work begun shall ever pause for death.
It is the love of Percival's sister for Galahad.
It is not that she is naturally a dreamer, that she would not have felt and enjoyed the realities of earth.

Her perceptions are keen, her nature expansive.

Browning, otherwise, would not have cared for her.