The first day

They won the war. The great tenma war is over. All the demon lords were able to defeat Ivraj and feldway. But not without sacrifice. Veldora died. Rimuru should be able to revive veldora through her soul corridor. But at the last moment, feldway was able to pull regalia dominion on veldora. He tried his best to resist but not on the price of his sworn friend. Only after his death, Rimuru understood her true feelings for veldora. It was not a bond of brother and sister, It was more than that. So with the help of ciel, she went back in time to save her soulmate.

Fem Rimuru x Veldora
(Rimuru isn't god level yet as she hasn't sent to the end of time and space. But he is powerful)