She tells him he has changed, and he knows she doesn't approve of it. But what could he do? Losing a hand... tends to change people. Changes perspectives on what's important, at least, when the most important part of him is now lost, but she would have none of it. She wants to cling on to the throne through any means possible. He came all this way to come back to her, only to come to the realisation that she wants power more than she wants him.
His visit with his father goes no better. He doesn't want to talk about his hand, but he has to, and the fury in his father's eyes had him almost lose the will to fight over resigning from the Kingsguard, marrying Margaery Tyrell and returning to Casterly Rock.
In that dreadful silence that ensues, he wonders for a fleeting moment if he might have been better off staying in chains as a hostage.
"You are not my son." Lord Tywin turns his face away. "You say you are the Lord Commander of the Kingsguard, and only that. Very well, ser. Go do your duty."