相思成疾念旧成疾
[xiāng sī chéng jí niàn jiù chéng jí]
The meaning of this username is quite poetic. It roughly translates to 'Thinking of you has made me sick; yearning for the past has made me sick'. It portrays a person suffering from unrequited love or missing someone so intensely that it affects their well-being. The term “disease” refers more to emotional state rather than physical illness.