The book is about MC who occasionally has dreams of the "future". I say that because in actual reality, MC is living a different timeline. Im assuming that her sisters, aka Liliana and Viola, reincarnated/time travelled back to when they were younger (a year before the execution), hence this novel is addressing the second life. MC, after having those dreams, decides to try and be a better sister, but after the first few (let's say 5-6) chapters, she gives up, as she realises that her sisters will never truly love her anyway. This changes when the day after she decides so, her sisters gain an epiphany (they came back after dying in their first life I'm assuming) and decide to be good sisters to her, seeing as how MC was still kind to them even when they were gonna die (in the first chapter).

From here it get a little rocky, because MC has already gone 18 years under their isolation and bullying, so being faced by their love and affection all of a sudden, she is very suspicious and terrified. She seeks advice and comfort under the ML in the temple that she calls her sanctuary, and decides to, like ML's advice, try to be naughty and get back at her sisters. This means that MC snapped at them 2 times and ran away. It gets better after that because the 3 reconcile. From then on, it's a quest to stop the future from turning out like her dreams (Liliana's ex fiancee supposedly being the reason for their family's demise, betrayals etc).