我愿做你的美人鱼永不劈腿我愿做你的小火车永不出轨
[wŏ yuàn zuò nĭ de mĕi rén yú yŏng bù pī tuĭ wŏ yuàn zuò nĭ de xiăo huŏ chē yŏng bù chū guĭ]
This name expresses a dedication and loyalty in a romantic relationship. The first part implies willingness to be one's mermaid, symbolizing unique and devoted love, and never 'cheating' or straying from that path. The second part about being a little train that will never 'go off the track' also conveys this idea of steadfastness.