Fiancés Fall in Love with My Sister.

Again and again, the story repeats itself, and Ilya is stuck reliving the same fate. No matter the circumstances, no matter what she does to avoid it, she cannot escape her future. Her fiancé, Soleil, will inevitably fall in love with Sylvia, her weak yet kind-hearted little sister, and Illya will be left alone.

At first, she thought she could change his mind, but that only caused feelings of resentment to sprout. She then tried to ignore their relationship, but her love for Soleil never wavered. In this endless loop, the feelings these three hold for one another never differ from those of the original timeline. Thus, along with Ilya's unfaltering love comes unfaltering despair, as she is trapped in time with her heart rent asunder each iteration.