The Classic

Keulraesik is a movie starring Son Ye-jin, In-Sung Jo, and Cho Seung-woo. A college student finds a diary detailing a long-ago love triangle involving her mother, her future father, and his best friend.
Ji-hae's friend is having problems expressing her feelings to the boy she loves, so she asks Ji-hae to write e-mails to him in her name. As the boy falls in love with her letters, Ji-hae discovers the story of her mother's romance which is remarkably similar to her own circumstances.