I think it's about an emotionally abusive relationship. When people are so paranoid, like the person she describes in the song, they'll often blame outside forces for their problems, never admitting that they have a problem. She seems to be telling him that no, she's not his paranoia, not his doomsday, he needs to just calm down and realize that the world is not coming to an end, and she can't be there to keep him in line all the time while all she does is get blamed.
I think it's about an emotionally abusive relationship. When people are so paranoid, like the person she describes in the song, they'll often blame outside forces for their problems, never admitting that they have a problem. She seems to be telling him that no, she's not his paranoia, not his doomsday, he needs to just calm down and realize that the world is not coming to an end, and she can't be there to keep him in line all the time while all she does is get blamed.