如果那天我没有爱上你
[rú guŏ nèi tiān wŏ méi yŏu ài shàng nĭ]
'If that day I had not fallen in love with you' implies a feeling of regret or a what-if scenario regarding a romantic relationship that perhaps ended badly. It indicates a contemplative mood, thinking about how life could have been different if that specific moment of falling in love had not happened.