They've met when they were about 15/16 basically didn't grow up together -> psychologically no sibling bond.
They used to be family for rather short time.
And their patents divorced about 7 years AGO. So they haven't been step siblings even by law for a long time.
And it looks like their parents won't remarry.
it did make me uncomfortable at first but now i see it as another portrayal of their "forbidden love" trope. also, i don't really think of them as step bros now cause they weren't even a family that long. aside from the fact that it's fiction, i admire how their relationship is portrayed after their parents divorced. if it really was just a fling or "curiosity" i doubt they would've kept in touch and continued being in each others lives. that's one metaphor i praise in the story
It's more about them being business partnery than real feelings at this point.
Joowon's father blamed Haesoo for Joowon's downfall (him falling for Haesoo) right into Haesoo's mum face.
Then they argued through phone call:
http://www.mangago.zone/read-manga/love_or_hate_yeongha/uu/ibx_chapter-86/pg-20/
With Haesoo's mum being disgusted with Joowon's father calculated and selfish behaviour.
So it doesn't look like they will remarry in the end.
She literally told him:
"Stop pretending to be a good man. You don't have our best interests at heart, so stop pretending to.
You are selfish, you know that? Don't use your son as an excuse".
Like she is completely done with that man. She is not only disgusted by his behaviour towards her and Haesoo but she is even disturbed how he wants to direct his own son's life like some puppet (and that he doesn't care about his son's opinion, he didn't contact Joowon first but his agency).
What's more Haesoo's mum finally starts to see that maybe she was also in the wrong.

i just gotta ask, what do you think about the step brother situation? like do yall just ignore that part of their relationship? or maybe because it aint blood relation it dont matter? i love jowoon and tbh i wouldnt be mad if they ended up together but the step bro situation is still kinda weird to me