生死不负的誓言冷彻心骨的背弃
[shēng sĭ bù fù de shì yán lĕng chè xīn gú de bèi qì]
A rather dramatic expression translating to 'an oath of loyalty until death contrasted by heart-wrenching betrayal'. It reflects the stark difference between grand promises made with one’s whole being and ultimate abandonment.