Itoshi no Ano Kata to Shiniwakarete Sennen: Kyou mo Watashi wa Akuyaku Reijou wo Enjimasu

"Swear... You won't fall in love with me." A thousand years ago, they were tragically torn apart. From then on, their souls have been bound, fated to be reincarnated together countless times. Yet they aren't meant to be. In every lifetime, he meets an unfortunate end. In this life, she's been reborn as Amelia, the daughter of a count. He lives again as William, the son of a marquess. "This time, I won't allow him to die!" Determined to defy fate, Amelia resolves to play the part of a cold-hearted lady to ensure they never fall in love. But, fate has other plans when William approaches her with a marriage proposal...?! (Source: MangaPlaza)