曾健忘但那个人我过目不忘现想忘可那个人但又忘不掉
[céng jiàn wàng dàn nèi gè rén wŏ guò mù bù wàng xiàn xiăng wàng kĕ nèi gè rén dàn yòu wàng bù diào]
Once forgetful, but now unforgettable. There is someone in memory, who can't be wiped off no matter how much you want to. This indicates a strong impression left by a particular person or event