Read manhwa That Man’s Secret Day / 彼の密かな一日 / 그 남자의 은밀한 하루
Haru works for a company that specializes in breaking up with people on behalf of their clients. One day, she mistakenly breaks up with the wrong person, who turns out to be her boss, Woo-Hyun. This mix-up leads to Woo-Hyun actually breaking up with his real partner. Feeling guilty, Haru is surprised when Woo-Hyun makes a proposition to her: “Let’s date for one year.”