My selfish younger sister is always taking my things and saying "I don't need this anymore" before throwing them away. But when she even took away my fiancé and discarded him, I decided to take revenge.

The older sister had her things constantly taken away by her younger sister, who always wanted what she had and would say "I don't need it anymore" right after. The parents spoiled the younger sister because she had a weak body due to asthma, but that illness had long since been cured. However, when the healthy older sister was chosen as the Crown Prince's fiancée, it was too late—even though the younger sister appealed that she was now healthy too. Due to a trap set by the younger sister who wanted the older sister's things, the older sister's engagement was broken off. After that, when the younger sister who became the fiancée said "I don't need this anymore" and dissolved her engagement with the Crown Prince, what trap did the furious older sister set for her younger sister?