Looking for a Book. I Read It a Long Time Ago, but I Can't Find It Now😭

At the beginning, a boy confessed to the heroine that he has always liked him. He harassed him every day. He was a domineering president. The heroine took the trouble to close the doors and windows to isolate the sounds outside. Playing on her mobile phone, she found a mini game in which the male protagonist could buy all kinds of good things with krypton gold.