I can't add much to anything everyone else has said, except that I'm pretty sure this song is connected to "Sparks Fly". Just a hunch, because in her notes in the Speak Now booklet, she says there are songs dedicated to her first love who she never expected to be her first heartbreak, and in the "Sparks Fly" lyrics, there's a part where she says "give me something that'll haunt me when you're not around". So "Sparks Fly" is part one of the love story, where they first fell in love, and Haunted is the follow-up, where he broke her heart.
I can't add much to anything everyone else has said, except that I'm pretty sure this song is connected to "Sparks Fly". Just a hunch, because in her notes in the Speak Now booklet, she says there are songs dedicated to her first love who she never expected to be her first heartbreak, and in the "Sparks Fly" lyrics, there's a part where she says "give me something that'll haunt me when you're not around". So "Sparks Fly" is part one of the love story, where they first fell in love, and Haunted is the follow-up, where he broke her heart.