Why is Cordelia's reaction handled as an aside?

King Lear

by William Shakespeare (excerpt)

LEAR. Meantime we shall express our darker purpose.

Give me the map there. Know we have divided

In three our kingdom; and 'tis our fast intent

To shake all cares and business from our age,

Conferring them on younger strengths while we

Unburthen'd crawl toward death. …Tell me, my daughters

(Since now we will divest us both of rule,

Interest of territory, cares of state),

Which of you shall we say doth love us most?

That we our largest bounty may extend

Where nature doth with merit challenge. Goneril,

Our eldest-born, speak first.

GONERIL. Sir, I love you more than words can wield the matter;

Dearer than eyesight, space, and liberty;

Beyond what can be valued, rich or rare;

No less than life, with grace, health, beauty, honour;

As much as child e'er lov'd, or father found;

A love that makes breath poor, and speech unable.

Beyond all manner of so much I love you.

CORDELIA. [aside] What shall Cordelia speak? Love, and be silent.