돌아선 네 뒷모습이 자꾸 눈에 밟혀

The line, explained

Some idioms you can guess; this one you cannot. 눈에 밟히다 literally says 'to be trampled by the eyes', and it means that an image keeps returning to your mind and will not let you rest. Koreans use it about a child's face when they leave for a trip, about a dog left at a shelter, and, in songs, about the last glimpse of someone who walked away. Today's line is that last case, and every word in it is doing the work of a camera.

돌아선 is 돌아서다, 'to turn around so as to face away', a compound of 돌다 (to turn) and 서다 (to stand). The modifier -ㄴ makes it 'turned-away', describing what follows. 네 뒷모습이 is 네, 'your', plus 뒷모습, one of those Korean words English lacks: 뒤 (behind) joined to 모습 (figure, appearance) with the linking ㅅ, meaning the way a person looks from behind. The subject marker 이 attaches because, in this idiom, the haunting image is the grammatical subject.

자꾸 is the adverb for unwelcome repetition, 'keeps on, over and over'. It almost always carries a shade of 'I wish it would stop'. 눈에 밟혀 is the idiom itself. 눈 is 'eye', 에 is 'at', and 밟혀 is the casual present of 밟히다, the passive of 밟다, 'to step on'. The image is strange and wonderful: the picture of you is lying in the path of my eyes, and every time I look anywhere I step on it. That is why 'haunt' is only an approximation; the Korean is more physical and more tender.

Register and use. 눈에 밟히다 is not slang and not formal; it is the vocabulary of ordinary emotion, the sort of thing a grandmother says about a grandchild and a ballad says about an ex. The subject is the thing you see, not the person who sees, so the pattern is X가 눈에 밟혀, never 내가 눈에 밟혀. Its cousins help it stick: 눈에 띄다 means something stands out and catches the eye; 눈에 선하다 means a memory is still vivid, as if in front of you. All three treat the eye as a place things happen to you.

Why the back and not the face? Korean culture handles goodbyes quietly; people bow, turn, and go, and the lingering image is a retreating coat rather than a tearful face. Whole generations of ballads are built on 뒷모습 for this reason. Try the swaps and listen to the idiom hold steady while the timing changes: 아직 눈에 밟혀 (still), 밤마다 눈에 밟혀 (every night), 온종일 눈에 밟혀 (all day long). The grammar never moves, only how long the image has been lying in the road.