Just last week, Katrina Kaif was spotted hastily leaving Arjun Kapoor's birthday bash

While initially it was believed that Kat apparently had a lover's tiff with her alleged beau Ranbir Kapoor, sources close to the actress say she left early as she had to shoot for her upcoming thriller with Aamir Khan.

Says Katrina, `I was in the middle of the shoot of a music track from Dhoom 3, which involves a lot of heavy-duty acrobatics, and hence left early. `

Also on why instead of RK, it was Arjun who saw her off at the doors, the source adds, `He is one of Katrina's closest friends and she was there only for him.

She was supposed to leave early but after the others insisted, she decided to stay back for a couple of hours before exiting the party. `