I see the style you're getting at right here. I don't really read this type of novel much, but I've enjoyed the few chapters I've read so far.
One thing I noticed right away is that the dialogue is a bit stiff. If you study how people talk closely, they pause every now and then, and even more so when they have intense emotions. In your prologue, you write:
The Duke held back burning tears forming in his eyes, "Oh, Milly. I miss you so much. That Luna girl, she can't be your child. So why? Why does she remind me of you?"
Instead of writing all the dialogue into one place, you can split it into more sentences or phrases to make a flowing chain that feels smoother as a reader to digest. You can also add in a touch more of emotion. For example:
The Duke held back burning tears forming in his eyes.
"Oh, Milly..." The words came out before he could stop himself.
Biting his tongue, he continued, "That Luna girl, she can't be your child."
The Duke looked up, eyes full of flaming sadness, "So why?"
"Why does she remind me of you?"
No one answered his pain.
The dialogue is a bit exaggerated also in some parts. You don't have to add more "o"s to "Hello" to make it flow. Instead, you can illustrate or narrate the protagonist's feelings and movements.
You don't have to necessarily add so many exclamation marks also. Yes, it makes Luna sound more childish, but as I said, it makes the words needlessly exaggerated, but it makes readers like me a bit uneasy. Instead, you can always narrate the enthusiasm in your text.
I'm really nitpicking at this point, but there are a few grammatical mistakes, so you can go back and edit the chapters if you want.
This is my personal style of writing and you can accept my advice if you want, so take it as a grain of salt if you wish.
All in all, hope this helps.
