@takachi
I'm guessing you've never met a sarcastic, honest person who does not sugar coat their words. We should meet, I would be your villain number one cause I'm Ji-Hwan in female skin.
The fact that he told her to "change her ways" means this is not the first time something like this happened. Not to such extremes, but some sort of conflicts 100% happened before and not once. Ji-Hwan told her a harsh truth she had to face ages ago. If she would not, next time would not be so lucky.
Telling her "Oh you poor thing" would do Seo-la no good. It will comfort her for five minutes, then she messes up again and dies. Real friends are not scared to tell the truth to people they care about if it will help them in the future to come. What Ji-Hwan told her, was a life saving advice, not some 5 minute worth pity.
If you can't tell a truth to a friend when they are clearly doing something wrong, you are not friends.
Me and my friends bicker all the time, call each other names and so on. One of my friends hates Frozen with passion so I constantly make Frozen related jokes. Guess what? We still hang out together, have fun and laugh. No forcing, he approaches me himself and sometimes replies in kind by mocking me for my shit 3D modelling skills. Are we offended? NOPE! We always have a good laugh together.
There is a big difference between mocking a non sarcastic person and a similar in kind. These two are similar.
It's only hurtful if other person does not understand sarcasm or is not similar in character. These two live on sarcasm, they fully understand each other. That's why they say things they do and still interact with each other and are not offended. Because there was nothing offending in those words.
It might not have been what Seo-la wanted to hear, but it defiantly was what she needed to hear.
@Halmoni
Tell me about it, happens so often -_-