i think the first scene depicted how mc wanted to escape the crushing reality of losing his loved one by drastically imagining suicide to ease his pain over dealing with the fact of seeing his lover die in a fire. at the last scene, it was revealed how the monster was actually the burnt, disfigured, and unrecognizable face of his lover which made him connect the idea of him to a monstrous being that made him fear this unknown man because that wasn’t the side of him that he knew. so i think, mc actually was caught in the fire trying to save his dead lover; survived, then was in a coma with that dream of accepting what had happened and processing the fact that his lover was hiding something grotesque from him.
Omg I’m going to cry
Yep, this is also my take, and that the rest of the one shot is us in his subconscious after the jump. The 'monster' who he thought saved him is a manifestation of his dead lover telling him to live and survive after his failed suicidal attempt. The end where the monster is revealed to be the burnt body of his dead lover seemed a lot more like acceptance of his reality (i.e., his lover died from the fire), and the 'thank you for coming back to me' was thanks for the visit but time for you to return to the land of the living because dead lover didn't want him to die. I did see WAku's post and its an interesting interpretation, but I don't think there's anything that directly points to the MC trying to save his lover from the fire - if anything, he realises in hindsight that there were signs he missed and he regrets not doing more.
Wait so at the last scene mc was in the hospital bed because he did jump on the first scene right?