姐的孤独你不懂哥的寂寞你不知
[jiĕ de gū dú nĭ bù dŏng gē de jì mò nĭ bù zhī]
You Won't Understand My Loneliness, You Don't Know His Solitude: Reflects on the loneliness or isolation felt by both genders, expressing the idea that no one understands these emotions truly.