Spolier to your spoiler.
Not rape exactly but kinda like coersion and pressure to have an heir. He was so sick and just lay there ... They thought he would die. So he consistently had to have sex with her untill she had a child. Sadly he loved her so much. But she told him feelings are not necessary.
Ooops! Im sorry! I had to reread the chapter with that part, Miriam’s age was not mentioned.. the age 26 was referring to him at the time.. sorry my memory was jumbled.
Spoiler ahead:
but he didn’t loved her..
“ “He spoke as if giving up. He looked like a warrior showing his vitals after taking off his armor. “Also, it seems there are many things you are misunderstanding about me, outside of that.”
“What do you mean?”
“Like how I loved the previous queen, Miriam.” He said Miriam’s name as if it were some kind of great insult.”

i havent finished reading the novel yet so i dont know the real reason behind sabelian’s mistreating blanche or abigail
as for the lack of chemistry between the main couple, i believe it’s more about how he built walls between them because 1) she was a villainess before dying, so of course after all she had done, he can’t come to trust her like magic yet and they didn’t even interact enough at this point in the webtoon for him to see she is literally a different person now and 2) i believe he has some sort of trauma or is haunted by his past wife? there are already hints of this in the webtoon too
i’m looking forward for the explanation tho! as they gradually start spending more time together, i guess their feelings will grow? also i like that we could read what he is thinking too in this latest chapter, it’s like the beginning of him noticing her for who she is now!!