The Poor Lady and Her Wonderful Miscalculation

The impoverished estate of Baron Aitreev has been blessed with two wonderful twin children. The kind and compassionate sister Belle and the intelligent and book-savvy brother Stephan have been living an increasingly modest lifestyle so that their people can continue to survive the seasons... though they are unsure how many more winters they can manage. Suddenly, a proposition comes to them from the servant of a well ornamented Marquis. The son of this Marquis, Evert Brotaire and his fiancée Elena Gromberg are displeased with their engagement and wish to find someone to marry out of love. It seems that this Marquis wishes for the twins to give the couple experiences of love, only to break their hearts and disappear so that the two will finally cling to one another and marry. The twins are hesitant to take such an underhanded job, but things change when they get the chance to meet this troubled couple...!

(Source: MangaPlaza)