Harry- Draco because ever since first year Draco would flirt with you at any chance he got.
Ron- George, yea I know he is his brother and everything but he see's the two of you hang out a lot and he can't help but get jealous but you assure him you just prank with George.
Fred- Ren McLaggen because Ren fancies you and everyone knows it.
George- Cedric Because of how all the girls fall for him one way or another and is afraid you will leave him for Cedric.
Cedric- Harry because you used to like him.
Draco- Everyone because that's just him.
Remus- Sirius. Even though Sirius is his friend and all but Sirius is known as a big flirt and all so it's kinda obvious as to why.....right?
Sirius- Severus. Yes as strange as it sounds he is jealous of snivellous. Why? Because you hang out with him a lot.
James- no one in particular, he will have his jealous moments though