是我孤陋寡闻不知你心有人
[shì wŏ gū lòu guă wén bù zhī nĭ xīn yŏu rén]
'It was my narrowness and limited knowledge not knowing that your heart belonged to someone,' this nickname admits a lack of awareness of the beloved object already having taken another lover and expresses feelings of sadness or humiliation associated with misunderstanding a romantic partner's attachment status.