Why did the Duke kill his wife in "My Last Duchess" by Robert Browning?
It occurs to me that there were several things the Duke could have done with his young wife if he decided he didn't want her. He was powerful enough to have gotten a divorce, even from the Catholic Church in those days. If not a divorce, he could have gotten an annulment. He could have simply arranged a separation, with his wife living in a distant place. He could have sent her back to live with her parents. Or, as Browning himself suggested, he could have had her confined to a convent. But the reason he had her killed was very likely to be able to marry again and collect another dowry. That is the main reason he has invited his visitor, the intended bride's father's representative, upstairs for a private talk.
The Duke seems to be an absolutely cold, unloving, insensitive, and cruel person who would be dissatisfied with a wife regardless of what she was like. He complains that she was too friendly and not sufficiently dignified, but it may have been simply that he got tired of her and wanted to try another wife with another dowry. He describes his last Duchess disapprovingly, but ironically everything he says about her only makes her seem more charming and lovable. In one place he tells his visitor that "...such stuff ... was cause enough / For calling up that spot of joy." He seems to dislike the idea that a wife of his should be joyful at all. He seems to want a beautiful youthful bride who would be just as cold as he is, but this is close to an impossibility, and the reader (as well as the Duke's visitor) must be appalled at the thought of what will happen to his next Duchess if the marriage is arranged.
The Duke is evidently not looking at his visitor while he is talking but looking at the portrait of his murdered wife and recalling how she displeased him with the very qualities in her person that Fra Pandolf managed to capture in his painting. The Duke calls the portrait "a wonder," but he could not see that his young wife was a much greater wonder, being real and alive and possibly even in love with her aristocratic husband, or at least excited by her new status as a Duchess.
A common theme in 19th century literature is the idea of the undisciplined gaze. Browning writes:
A heart—how shall I say?—too soon made glad,
Too easily impressed; she liked whate’er
She looked on, and her looks went everywhere."
This comments on how the duchess, while, sweet, let her eyes stray where they should not go. In short, he thought of her as a flirt. He believed she cared more about others than he, and his jealousy caused him to kill her.
There is also the point that in death he has the control that he felt he never had while she was alive. No one puts aside that curtain but him and so only those whom he chooses to reveal the painting to are able to see her.
At e d he look at portrait of the the last duchess and called "a wonder
The duke killed because he want a new wife