King Lear is a complex character, exhibiting both rational and irrational behavior. He is getting older, and as such wants to distribute his kingdom equally between his three daughters. Somewhat eccentric in his desires and beliefs, as well as his expectations, Lear puts a condition on the equal distribution of his kingdom.
He wants an open expression of love and respect from each of his daughters, as proof that they are deserving of their inheritance. When he does not get what he wants from Cordelia, the daughter that really loves him, he disinherits her on the spot. This behavior illustrates King Lear's shortsighted view on love and his misinterpretation of respect.
He expects to be honored and respected by his other two daughters, so when he divides the kingdom between them, he is unprepared for the way that he is treated. He is shocked by the lack of regard his daughters have for his needs, he still wants to be obeyed, even though he is no longer in charge. This leads to despondency and the beginning of madness for the King, as he feels like a misfit, an unwanted, unloved reject.
"Despite his tragic hubris, King Lear is a commanding figure. He is presented to us by Shakespeare as a majestic monarch at the pinnacle of his power. His stately presence is ushered into view by the pomp and trumpets. We soon learn that during his lengthy tenure as the realm's sovereign, Lear has served well, adding to the commonwealth's prosperity and estate."