孤独成性久病成欢
[gū dú chéng xìng jiŭ bìng chéng huān]
'Gu Du Cheng Xing Jiu Bing Cheng Huan' translates to 'Loneliness became a habit, and prolonged suffering turned into joy.' This suggests someone who has embraced loneliness and found a kind of twisted contentment in it due to enduring hardships over time.