时光不允许我回头后悔
[shí guāng bù yŭn xŭ wŏ huí tóu hòu huĭ]
'Shiguang bufenyun wo huishoubuhui'(Time won't let me turn back and regret) refers to the fact that what has happened cannot be reversed. In other words, time does not provide opportunities for turning back or feeling regrets, implying we have to accept past choices and look forward.