你结婚那天我当伴娘当什么伴娘你是新娘
[nĭ jié hūn nèi tiān wŏ dāng bàn niáng dāng shén me bàn niáng nĭ shì xīn niáng]
A play on the words of disappointment or unrequited love - the person expresses a deep emotional attachment that will never be fulfilled, as they see someone else in the place they wished to be.