Suddenly I Decided to Become the Female Lead (Pre-serialization)

One day, Ludia Mertens wakes up inside a romance fantasy novel as the best friend of Elian, the crown prince’s obsessive stalker. To avoid getting caught in Elian’s madness and dying like in the original story, she tries to keep them apart. But to her shock, she somehow ends up seducing the prince instead. Tired of Elian’s mean girl behavior and nudged by the prince’s cousin to date him, Ludia decides that if fate won’t protect her, she might as well steal the heroine’s role out of spite! (Source: Tapas)