ok so i think that in the 1st timeline chela became a magic supplier, and she was the dude magic supplier, he probaby needed large amounts of mana to live, and by the looks of it he treated like an object at first, just a living battery, im guessing in time they fell in love and got married, but by that point she was almost drained of mana, so she died, the dude realizing it was his fault, used all the mana accumulated over the years to go back in time and try to save her, leaving him almost dry and on death door, so he doesnt have much time to save her...
fuck me...it this is how it went, then saving her by making her become a witch will in turn prevent them from meeting and he will just disappear coz paradox?
fuck if i know but im sure its gonna be sad as hell
PD: THIS IS JUST A THEORY, I HAVE NOT SEEN THE RAWS, I HAVENT READ ANY WN OR LN, THIS IS JUST A WILD GUESS