|It's Soah. Reasons below, for those who haven't read the latest scanlated volume:
Spoiler (highlight to view)
Remember the old guy who appeared in Chapter 33 and 34, the one who said that "The girl you are thinking of is not the one meant for you."? He was lying, as was explained in Chapter 59 while Suh Wang Mo (Habaek's mother) and the old guy were talking. Suh Wang Mo requested that the old guy lie to Habaek, to say that he wasn't fated to be with Soah. This was to avoid the suffering and pain that she knew Habaek was going to experience if he didn't avoid fate.
But as we saw in Chapter 34, Habaek said "If it's not her (Soah), I don't want to know. I will break destiny." This showed that even if Soah wasn't the one meant for him, he was willing to fight fate. But as we all know, the old guy lied, that's why the old guy said to Suh Wang Mo in Chapter 59 "That child chose his own fate of his own volition." So Soah really is his fated person. :D
Hope it wasn't too long. XD