Looking for the title of a manhwa

Hi! I'm looking for a shoujo manhwa which I actually don't really remember the plot lol but I'll try, so the FL has a long hair (i forgor the color) where she got reincarnated after getting k*lled and betrayed/falsely accused by her own comrades (a knighthood/civalry) (the plot is something related to clearing the dungeon k*lling monsters or something related to it) and the ML is a black haired captain from different knighthood also an emperor/duke but is cursed? but even knowing that the FL decided to join hands with the ML in her second life than joining back to her past knighthood.. that's all that I can remember from the plot, so if any of you have read the manhwa or had the slightest idea about the title please help me, thank you!