Midnight Train by Sam Smith is a poignant ballad that explores themes of love, heartbreak, and the difficult decision of leaving someone behind for self-preservation. The song speaks about the emotional journey of walking away from a relationship despite the deep feelings involved. Key moments include the metaphor of a 'midnight train' symbolizing a sudden and irreversible departure, and the vulnerability conveyed in lines about struggling with the decision. The song's haunting melodies enhance its emotional depth, making it a relatable yet heart-wrenching narrative of love and loss.