im not sure if you want spoiler, but reas ahead if you like
this is only their first time so he doesn't knot, but if i remember correctly they do talk abt knotting and i think heesong doesn't want to but they don't really reach a conclusion (? im sorry it's a little bit foggy in my mind ) but yoon chi young gets another phermone shock later on after this and he loses control that's when he first knots and it's def more forceful/rough but i wouldn't say it's that bad ngl im not sure if it was unconsensual knotting or not but it was def rougher than this
after that one time it goes back to sex like this, they do have a lot of sex later on and there's some stuff that's a little weird but it's not bad, just awkward (at least for me)
I was a lil scared abt this since the people who read the novel said this sex scene apparently involved unconsensual knotting and it wasnt very great but here it looks fine and it didn't include that so im glad