Not sure how far it is in the story but the Duke will definitely come home and would even joke about how he's the 'dad' since Arellyn calls the secretary her 'mom.'
P.S. major spoilers ahead
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The duke is not Arellyn's father, he is her uncle. Her mother the duke's sister who got married to the emperor (iirc) of another nation but the emperor also is not Arellyn's father. I think it's still unknown who her real father is since her mother ran away from the emperor.

Hi! Does someone know when will her Father go home? Is it still far or not? I love the story but I just hope that it won't drag anymore and want to know about them or what really happened to their family