A Green Eyed Monster
George Weasley will never admit that he gets jealous. Padma can tease him about it all she wants but he is just too darn stubborn to admit that he gets possessive just like the rest of them. His pride is too strong for that you see, and Padma would have never known his true feelings if she hadn't said yes to a certain handsome Ravenclaw.
And she jokes about him, and how dashing and charming he is, just to drive George mad.
And it always works.