提笔忘字也忘你
[tí bĭ wàng zì yĕ wàng nĭ]
It translates into "Forgot how to write characters, and forgot you while picking up a pen." This is poetic, expressing the forgetfulness so deep and broad that even when it comes to writing Chinese characters (something learned from childhood), they can't recall it, not to mention 'you', implying strong emotions towards someone, either because of pain, love, or time that has caused them to fade away in memory.