I saw this post on fb finding the sauce yet up until now no one in the comment section knows it yet so help meee ಠ ೧ ಠ the post goes like this "There's an omega who got impregnated by an alpha (of course) but the alpha reject him. Their compatibility is 100% but after he gave birth the alpha let him signed a contract that he will change his pheromones to 0% compatibility of the alpha pheromones. remember that the omega have a friend. That the omega's pheromones was lavender."
Its called perfect match / Chinese Title: 最佳契合 / PM
I found the english translation web novel version of it here : https://blackbox-tl.com/novels/pm/pm-chapter-1/
They are angels. The uke is the teacher and the seme was the student. They got married already. I was able to find a screenshot on my phone from this bl, it has a dialogue where a side character seme said "It hurt? The pain is good, next time I'll see you like this, I swear I'll fuck you until you die"
Kurona my baby boy let's goooo