Here I thought the Duke was a terrible person and husband. Who in the hell flaunts their mistress in front of their legal wife? You realize this is noble society right? Her family and their faction can make things really, really hard on you.
Still I must apologize to the Duke.
I thought he was stupid, immature and naive but I had no idea he was actually mentally retarded.
Sure divorce the woman you married for money. Tomorrow all the whispers in the noble courts will be that he took her dowry and then discarded her once it was all spent. No one will be willing to marry him then and more pointedly, his creditors will likely cut him off. Reasonably at this point they are still extending loans with the tacit understanding that the Duke's in laws could underwrite them if necessary. Doing something so cruel to a woman of the blood publicly would easily make him persona non grata among other noble women. Who would want a husband that siphons off your money to care for his mistress while leaving the legal wife to live in misery? People would question if he was worthy to be a man let alone a noble. Propriety dear boy, surely you have heard of it? It is okay in noble society at the time to have a mistress or two if your wife grants you permission or you are discreet about it. To abuse your legal wife while exalting your mistress.... well let's just say that you'll find few friends in court that way.
And bravo to our heroine. She endured it longer than was reasonable for most people. She must have the patience of a Buddha. She could have used the almighty power of money at any time to run the Duke out of house and home but she endured it until now. Divorce her? The Duke is already lucky she hasn't divorced HIM.