Why did the Dukeeliminate his last Duchess?

The Duke eliminated his duchess because of the way she treated him much like how she treated other men and didn’t value him as much as her thought he deserved. His actions were caused by her simplicity to blush and need to thank men, in ways unknown to us. Some particular incidents were that every little compliment she received from a man she would blush and she believed that almost everything said to her was a compliment; she was very easily made happy. Then when the Duke commanded her to do something all of her smiles she gave him stopped. Since she stopped loving him because of that one comment he decided that she didn’t value him to his true extent, he decided he had no value for her either. But, towards the end of the poem you see that he somewhat regrets his decision that he made to eliminate her and now wants her back.  Due to the fact that his deeds are done and he cannot take them back he only has a painting of her to remember her by. Her smile caused all of this drama that, sadly, cannot be undone.