You understood most of it, they were once lovers, she was married off to the other guy. In the end at her funeral, as a statement of his undying love for her, he’s playing the qeej instrument to guide them as he walks ahead of her to lead her in her path to the afterlife. They reach the river where the path they took together ends, as he must come back to the physical side and she must continue to the spiritual side of the underworld. They will part ways here to never see one another again. 😭😭😭