From the last panel of the recent chapter, it looked like Mavis and zeref were in love and that single magic turned out to be a creation made from love but suddenly zeref got crazy and they two fought each other where single magic reincarnated again but from darkness this time and to stop him ,Mavis sacrificed herself and sealed herself in what we known as lumen histoire and that was done by the most powerful magic "fairy heart". That's why there was two crossed out line on the last page of fairy tail zero. First one was when single magic was created from their love and second was when they fought each other and when she got sealed in lumen histoire to protect the world from darkness. And when this news reached to the Mavis team, yuriy got angry and fought zeref and died. That's why his death date was there after that second crossed-out line.
But why zeref wanted that magic from darkness. Zeref wanted E.N.D to kill him just after he got possessed by that evil spirit so maybe to unlock E.N.D it requires lumen histoire, so that he could die and repent for his sins of destroying everything whenever he values life.
But why zeref wanted that magic from darkness. Zeref wanted E.N.D to kill him just after he got possessed by that evil spirit so maybe to unlock E.N.D it requires lumen histoire, so that he could die and repent for his sins of destroying everything whenever he values life.