是我孤陋寡闻不知你有人
[shì wŏ gū lòu guă wén bù zhī nĭ yŏu rén]
This translates to 'it is my narrow-mindedness not knowing you are taken,' indicating humility and awareness of one's ignorance about a specific situation, possibly expressing regretful misunderstanding about another person's relationship status or engagements.