My last duchess how does the revelation in lines 45-47 impact the development of the duke's character over the course of the poem

The Duke is conversing with an emissary of a tally. The Duke is attempting to wed the check's little girl, so he is endeavoring to awe the emissary. In portraying the sketch of his latest duchess, he imparts more about himself than he does of his late spouse. He takes note of that the Duchess' look of "euphoria" in the work of art is not on the grounds that he was available amid the artistic creation.