Harry- Ginny Weasley because you know she has a crush on Harry.
Ron- Hermione Granger because it's obvious to everyone that she has feeling for Ron and it doesn't help that the two of them are close.
Fred- some Hufflepuff girl you don't really remember her name but she's always talking to Fred.
George- Angela Johnson because they used to date.
Cedric- Cho Chang....well what could you say everybody knows how she practically obsessed with Cedric.
Draco- Pansy Parkinson because they are best friends.
Remus- No one really.
Sirius- Almost every girl in school. And you can't really help it because before you and him dated he was known as the man whore and practically dated every female in the school.
James- Lily Evans because he used to like her.