...if you put little hearts by their names on your notebooks.
...if you start dreaming about them in human form doing...all sorts of things.
...if you start dreaming about yourself in anime form doing all sorts of things with them.
...if you start talking like the characters do in the form.
...if you quote some of their dialogue in a message, without looking it up or using any references.
...if you sigh everytime you hear, read, or sense their name or face on a picture.
...if you have read M rated fanfics of them and replace the other persons name with yours throughout the story.