Could it be SH scars?
I saw that theory and it could be ofc, but that is why I included the second part that she and her behaviour doesn't strike me as SH. Also I think Mincheol would be on his toes all the time and be constantly checking on her in some way, and so far we didn't see that happening. Also the manhwa doesn't seem to be in such a dark tone, but it would be interesting if SH was mentioned/included and done right. However, I have to say that I think Mincheols injury will be linked to Haneul in some way, because it usually is done in that type of manner in the romance genre in general (and its not like they didn't know each other before for the injury to be their linking point and be included in that way).
ALSO, just thought this.
If the author played the card of Mincheol going to business major without the injury, I would be inclined to think that is his way of keeping an eye on her because of SH, so he could be closer to her and take care of her. But with the injury added, I don't think that is the case.
LOL I read so many psychological/diabolical manhwa where they inflict the injury on themselfs so it would seem like an accident and so they could be closer to the love interest, but again this manhwa is not that type of genre I think (AND HOPE LOL).
I'm calling it now. I think they had some sort of accident before college.
Mincheol is a sporty person and we see in the latest chapter that he has an injury cause he had to stop running (chapter 28). It has been bugging me (from chap 18) when it was revealed that Mincheol wanted to go to Phys ed and did a lot of sports in highschool, but is now in the business major. I thought it had something to do with Haneul and was scared tbh that the only reason he didn't go to that major was so he could be closer to her, but now I see that is not the case and is actually because he couldn't go cause of the injury.
When we pair this with the fact that she is always seen wearing her wristband, I think she may be covering a scar from that accident and that Mincheol possibly gave her that wristband.
She doesn't strike me as a person that is self harming, and I don't see the characters around her and her close friends being wary of her mood, that type of tendencies or generally behaving in any way that would indicate that.
ALSO I analyzed all the scenes from the flashbacks and she is not seen wearing the wristband in either middle or highschool. Also maybe something will be revealed at the reunion, cause Mincheols injury storyline has been building up to this point.
I would like to hear what the rest of you think? (=・ω・=)