(Beware of spoilers)
Nicole had always had a crush on Harry, so when he died, she and Harry exchanged lives.
However, she returned to her past.
Gradually, she realized that this was not a rebirth in the ordinary sense.
Here is another parallel space. (Time passes at the same speed in all space-time)
The original world continues and a new story begins.
Tentative space line:
One-line: The world that Nicole originally lived in has ended the war.
Second Line: The same world as First Line, except that the time was when Nicole was two years old, so Nicole began to change the "future".
Third Line: The Original World
Fourth Line: The world where Harry and Draco are together after the war.
Five Lines: The world where readers of this book live, in the 21st century, there are Harry+Potter series of books and fan fiction
Note: The medium of time travel is Nicole's "Life Exchange" book
Intention: The meaning of life may be happiness...