Mistaken

"The words are the last thing your soulmate will say to you." Hermione blinked. "Well, how does anyone know that they're with their soulmate then? You wouldn't know until one of them dies." Hermione hears about the words witches and wizards have on their arms and is led to believe her soulmate is one person, only to realise in the end that it had been another the whole time.