I think Jiwon said this.

Okay so i just read chapter 25 and im 100% positive that he was calling out his ex lovers name

OMGGGGGG IM SORRY FOR WHOEVER READ THAT REPLY ABOVE I DID NOT INTEND FOR SPOILERS!!!!!

가지마 means don’t leave.almost the same with 하지마 which means don’t do it. I think he dreams of his ex leaving him and he don’t want the ex to leave him.

yeah gajima isn't a name lol, it really does mean don't leave

Exactly

Ga ji ma is not a name, it means “please don’t go”. I learn basic korean
There’s no way a hangul name ga ji ma

O-ke-i thank you~

That isn't what happened though. He doesn't want his ex, he loved him, but this trust was completely abused, to the extent where he wishes the relationship never happened, and it's legacy meant he hasn't had another since and has been very guarded in all aspects of his life. The last thing he remembers saying to his ex, was asking him something like how long has he been cheating on him, did he ever love him, were those words just a lie, and telling him not to laugh at him.

Thanks for the explanation because I didn’t read the raw yet to know the continuation chapter.So i guess it doesn’t related whether he don’t want his ex to leave or not.

Nope, it's just Jiwon being unguarded due to the help of alcohol. The emotional dependency he showed, probably triggered the memories he had with his ex, which gave him a nightmare. His relationship with the ex was the only and last time, he apparently was ever involved with anyone on such a level, and the ex threw it back in his face which has left quite a legacy for Jiwon. He was maybe 18/19 when it started presuming it was his final year of school. I guess maybe also, Jiwon might see his own past self in DG, and so he knows the harm that can be caused with a failed relationship, hence why he acts defensively by avoiding him earlier rather than showing him his weak points, their conversation where Jiwon asked him directly was maybe so he could get some reassurance, and also to get DG to be honest too (as previously DG too was trying to deflect with small talk). Anyway, thats enough with these bad vague spoilers, Chap 36 looks like they will have a proper conversation, well hopefully. (⌒▽⌒) Maybe DG will be confident enough to start calling Jiwon by his actual name now, rather than just sunbae.