So Lear is trying to ensure the peaceful passing of his power and responsibilities to the next generation, though his methods are unusual.

Goneril and Regan, at least on the surface, are showing dutiful reverence for their father. Cordelia on the other hand, seems to lack proper respect. But the whole point of the play is that surface appearances sometimes deceive. When Cordelia says

“Good my lord,

You have begot me, bred me, loved me: I

Return those duties back as are right fit,

Obey you, love you, and most honour you.

Why have my sisters husbands, if they say

They love you all? Haply, when I shall wed,

That lord whose hand must take my plight shall carry

Half my love with him, half my care and duty:

Sure, I shall never marry like my sisters,

[To love my father all].”

she is showing a deeper understanding of the responsibilities of a daughter AND of a ruler to honor all obligations and strive to balance them. Lear, by disowning her, is on the surface honoring his obligations but on a deeper level is betraying them by requiring of his daughter more than is due even a father or a king.

Of course, the conflict is somewhat resolved later in the play.