I think the mom just wanted the best suitor with the best assets and not just some ‘mutt’ as she says
They are a woman (I believe) I think it is just about the money. We see the duke earlier on and the empress was talking about how rich they were. The empress wanted power and money which the duke had and in exchange for it she sold her daughter. More like an auction on who had the highest offer. I don't think the empress was ever homophobic, and it might just be that the duke is the head of the house which we see. It is just a title, I would rather be called the duke (back then) than duchess, sounds a little more authoritative.
But who knows ヾ(❀╹◡╹)ﾉ~
guys i think im stupid but wasnt duke lorenz obviously a woman? because of their bust? im just confused since wasnt the mom homophobic and ppl refer to lorenz as a duke (which is a male)
or maybe they trans idk