Ryuu Taikou no Senzoku Jijo wa Goenryo shitai!: Tensei-saki no Okyuuji Aite wa Zense no Moto Konyakusha deshita

On her sixteenth birthday, Viscountess Mille-Feuille Forêt Noire, a member of a long-lived race called dragonkin, remembers her previous life as the murdered fiancée of Dragon Duke Vacherin. She immediately vows never to get involved with him again and aspires to live a peaceful life by hiding what she knows, but after a twist of fate or two...she soon winds up the Dragon Duke's personal attendant! Past intrigue now begins to yield problems in the present. Who killed Mille-Feuille in her last life? How can she improve the lives of fellow dragonkin women? Is she in love with the Dragon Duke, or are her feelings just lingering attachment from their old romance? And how will this all affect her new relationship with her former fiancé? History may or may not repeat itself in this romantic fantasy!

(Source: J-Novel Club)