Here is the full list of all 8 Heart and Seoul achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
Choose all the "funny options" during the job interview
Choose to return to Daegu
Reject Seok-Jin
Reject Hyun-Woo
Choose to stay in Seoul
Get Hyun-Woo confesses his love for you
Seok-Jin confesses his love for you
Achieve all endings