I guess they got hit by that truck and their fates got smashed together, idk? I know in my head I should find this confusing, but I don't for some reason
Its pretty obvious Dojun (ML) only has seen the tutor as how their relationship should be, a teacher-student. He never formed any romantic feeling but felt regret for what not asking and saying what he wanted to the tutor before pulling the plug. Even with how perfect Dojun's life is, having to be requested to pull the life support of some else's life must have still been a big dilemma for him. Coz of Dojun's regret which intersect with Jaewon's novel isekai (which actually isnt an isekai bro just went back in time as well) he too ended going back in time exactly at the moment of his past he wanted to change.
What just happened.. Like how did the black haired guy feel towards the tutor and he regressed back in time??????? What about the bottomm?????? Did I even understand that correctly