a ghost
When someone says they love you, and the only reply is 'Ditto', like a total fake.
He said he loved her, and she just said 'Ditto' like she was bored.
She told him she was in love, and he just said 'Ditto' like he had no feelings.
He said he adored her, and she just said 'Ditto' like it was a chore.