你认为我刀枪不入我以为你百毒不侵
[nĭ rèn wéi wŏ dāo qiāng bù rù wŏ yĭ wéi nĭ băi dú bù qīn]
'You Thought I Was Indestructible, I Thought You Were Immune to Harm' captures mutual misunderstandings in relationships where both partners believed each other stronger or invincible than actually were; it expresses the irony and pain after realizing the truth.