凉情凉心百毒不侵空城空心刀枪不入
[liáng qíng liáng xīn băi dú bù qīn kōng chéng kōng xīn dāo qiāng bù rù]
This phrase depicts an emotionally hardened and impervious state where love has made one cold-hearted yet untouchable, suggesting defenses against further emotional pain.