Cultural allusion: the belt is getting wider and wider.
It means that you have lost weight because of lovesickness and your clothes look fat. Still thin.
The original "Ancient Poetry" said: "The day of parting is far away, and the day of clothing is slow."
Quote Song Liu Yong's "Die Lian Hua": "I don't regret that the belt is getting wider and wider, which will make people gaunt." Shi's poem "Death" said: "My clothes are getting wider and wider, and the new book has increased my haggard."