The friends first appeared together in the 2008 romance Bachna Ae Haseeno.
A source told The Times of India: "Even when Ranbir was dating Deepika and Katrina, he usually confided in Bipasha about everything. Likewise, she would also share her innermost thoughts and fears with him.
"Obviously, post [Bipasha's] break-up, one of the people she has been confiding in is Ranbir."
However, she denied the rumours, reiterating that they are just friends.
The Dum Maaro Dum actress recently broke up with John Abraham, her boyfriend of ten years, and has since been romantically linked to Josh Hartnett and co-star Rana Daggubati.