我姓刘却也留不住你
[wŏ xìng liú què yĕ liú bù zhù nĭ]
This user name means 'Although my surname is Liu, I can't keep you with me.' It expresses a kind of helpless sorrow about a separation or the impermanence in one's life, suggesting that no matter what the background or origin (in this context, represented by surname), certain changes or departures are difficult to prevent.