
Since in the original novel the ending is "open-ended" with multiple dimension scenarios. For example in one dimension Athy ends up with Lucas and in another she ends up with Izikiel but also in another dimension Diana doesn't die.
I hope somehow we get a "Why are you doing this to me, my duke" type reset button where we can restart the story and this time Diana lives. I think of all the characters she deserves the best ending. Her backstory and fate is the most tragic.
Sold off as a "tribute" to a foreign country to serve as a concubine, confined to a foreign palace, dies at a young age from childbirth. she KNOWS that the child she is carrying, is slowly killing her and she will never see them grow up but still she chooses the love she has for her unborn child over herself.

SPOILERS!
A pathetic passive cuckold.
The "mother" has no right to pass judgement on the FL when she cheated on her husband with his brother and got pregnant. Blaming "loneliness" as the reason because her husband was working. lol bitch do you have a job? then get one if you had too much spare time on your hands, don't fuck your brother-in-law.
As for the "brother" I suspect he is actually adopted since the ML's "father hinted the reason why his wife couldn't get pregnant for many years was due to fertility problems they had. When she got pregnant with his bro's baby it sorta confirmed the problem is most likely not hers but her husband. Also, the "brother" doesn't look anything like the parents.

Because there are elements in this that aren't traced where the difference is ability is huge when compared to other components that are near identical that from WMMAP - the "good" bits.
look at the clock and desk in the link below.
the artist fails perspective drawing.
http://www.mangago.zone/read-manga/the_promised_queen/uu/nml_chapter-10/pg-2/

Have become defacto nannies to the twins and seem to be adapting nicely to their new duties.
http://www.mangago.zone/read-manga/i_gave_birth_to_the_tyrant_s_child/uu/nml_chapter-19/pg-8/
http://www.mangago.zone/read-manga/i_gave_birth_to_the_tyrant_s_child/uu/nml_chapter-21/pg-13/
If there is way we can save our Goddess Diana :(
Jeanette could have both ML's for all I care if Athy gets to have her mommy.
Second (or evenly matched)to Claude, Diana has the most tragic backstory and definitely the most tragic fate.
1. Given to a foreign country as "tribute" to serve as a concubine to a foreign Emperor and be confined to a foreign palace despite being a "free-spirit".
2. Know that the child inside you is killing you slowly from within and that you will NEVER see them grow up. And that their birth means your death.
3. Die at a young age at the prime of your youth.
4. The only time you get to meet your only daughter is as a lost wandering figment of your soul within your ex's manastream/psyche and that "finding peace" means saying goodbye forever.
Despite all this, Diana never held any anguish against anyone nor lost her smile. She truly was a beautiful soul.