Apparently, Ileana and Shahid got along like a house on fire during the film's rehearsals. Which is probably why Shahid has been addressing Ileana as 'Ranbir's girl'. A source from the sets told TOI, "Ileana had a great time working with Ranbir on Barfi!
She shared some of those experiences with Shahid, who has now started teasing her as 'Ranbir's girl'. Shahid is being plain mischievous. Besides, Ileana knows only two actors so well; one being Ranbir and the other Shahid."