So... for what I can collect, the first 5 chapters are simply the 1st chapter split in 5?
Either way, those serve as a prelude, showing us what seems to be their two past lives, in both lives they were destined to fall in love, but ultimately meet a sorrowful ending, however, at the end of chapter 5 or part 5, call it whatever, he is given the opportunity to change his fate in a next life. Or that's what I've collected.