While Ranbir was away with friend and director Imtiaz Ali for the screening of Anurag Kashyap's Gangs of Wasseypur 2, Kat's car entered RK's Bandra bungalow. It was quite while later that Ranbir came back home.
In the case that parents Neetu and Rishi Kapoor were home, it seems like they have accepted Kat as their son's girlfriend. It's common knowledge that Neetu is always tuned to Ranbir's life and he keeps no secrets from her. Rishi too has acted along with Katrina and is said to be fond of the girl. So did Katrina 'hang out' with the parents before spending time with Ranbir? We certainly hope so!
And in the case that the parents weren't at home, we'd rather leave the young couple alone, don't you think?