According Jaewoo's ramblings about the original plot, Mujin and Hyjeon hated each others' guts at the start. Hyjeon's being in Mujin's debt and Mujin's personally took the opportunity to harrass and abused Hyjeon at every turn, but they eventually fell in love. So there must've been something they like about each other fundamentally, once they got to know about each other, after spending enough time together. To me, it sounded like the two main leads in the original plot had a much rougher relationship than here, yet they managed to fall in love. Even setting that aside, as of now, Hyjeon is already finding comfort in having Mujin coming around. So if Jaewoo didn't re-appear, the original main couple will most likely end up together once more
from what i remember of him describing the plot after mujin was saved he ended up helping him with his debt probably in a similar way with how he was with jaewoo so in a contrived way but it didnt really seem like he tormented him that much. i think the comfort it purely because their mutual relationship with jaewoo and nothing related to mujin. i also would t be surprised is hyjeon partially blanes mujin for jaewoos death as well. considering how far off course their relationship veered i dont personally see them ever getting together having been in the cards
hypothetically, if jaewoo stays in the real world, would hyeonjin get with mujin instead and follow the original storyline?