Never-Ending Darling

Ha-im Yun lives in a world where people register their DNA into cloning databases, a world where human suffering has basically been eradicated. The brilliant mind behind this cloning technology is none other than Ha-im's boyfriend of five years, Geunhu Ji. Their relationship isn't perfect, but they make it work—or so Ha-im thinks, until she finds a dead body at her boyfriend's house... and the dead body is hers. The next day, she wakes up with no recollection of the previous day until she finds a note from herself in her room... "Ha-im, if you're reading this, you're a clone."

(Source: Webtoon Entertainment)