Responses

No he did his job. He might have been the one that told him but it was bound to come out eventually. Plus he was doing it out of concern, he though she might, you know, die. Plus he is the head butler that reports to the duke not the duchess. So his job is to tell the duke what’s happening in the dukes home. Also he gave her a chance to tell the duke herself and she didn’t for weeks. He can have all the sympathy from me. He deserves it. He is being blamed for their miscommunication/misunderstandings.
Look, I understand why he did it, but it doesn't change the fact that the entire situation they are in is because he couldn't respect Lucia's wishes and wait for HER to talk with the duke. Instead he pushed the topic and discussed it without her permission. So, yeah you did make matters worse, TWICE now. Good job. Please, feel guilty because you're getting absolutely ZERO sympathy from this reader.
As for the fight and our couple's stubbornness and pride... yeah it's frustrating. The duke is upset because he failed to notice something so important about her even after starting to care. She's mad at herself for developing feelings and wanting more. They need to talk, not be pushed into confrontation (again, Jerome is the one instigating it!!!)