The King of Hell Is Actually My Dead Boyfriend

Trying to Find a Book I Really Loved Before (Please Help!)

I read it last year. It was a romance novel, kind of like an infinite-flow story. The heroine went through maybe four or five worlds, and the male lead was the same person each time, but with a different personality. The story I remember best was about a train conductor, I think. Please help (⋟﹏⋞)