Some say that it's his alleged coziness to his Rockstar co-star Nargis that is causing issues between Kat and him.
But a rather reliable source also tells us that things are getting sour between Kat and him because the 27-year-old is not willing to marry Katrina who allegedly is insisting on having a rock on her finger.
A source tells us, "It was only incidental that Ranbir fondness for Nargis increased recently. However, what has really distanced him from Katrina is her demand that they get married, by March 2012, if not December 2011. She clearly told him that they should tie the knot in a year's time."
Katrina on her end claims these rumours are tommyrot. "These rumours are embarrassing, ugly, a million miles from the truth, beyond fiction.
The so-called people close to me who are saying these things actually have no proximity to me Ranbir is a friend, but there is nothing beyond. So there is no question of my breaking up with him or asking for marriage."
Well, wedding bells were chiming in Kat's head some time ago, when in an interview she told Mumbai Mirror, on 25 Jan 2010 to be specific, that she wanted to get hitched in 2012.
However, the Rajneeti actor, who has been dating Kat for nearly two years, ever since they worked together on Rajkumar Santoshi Ajab Prem Ki Ghazab Kahaani, seems to be taken aback by her demands.
The source explains Ranbir's bewilderment, saying, "Well, he didn't know what to do. He explained to Katrina that marrying her in a year's time wouldn't be possible since he is too young. Ranbir doesn't want to pin himself down in life."
Think of it, Katrina was more demanding than Deepika in her relationship with Ranbir. While Deepika asked for commitment, Katrina asked for shaadi, claims our source.
Reconciliation between the two lovers is not ruled out, says our source. "It would be more apt to say that they have had a big fight at the moment, rather than to say that they have ended their relationship.
Katrina would love to get back with Ranbir, who also likes her very much. But he is certainly not thinking in terms of marriage with her at this point of time."
It may be recalled that Mumbai Mirror (November 3, 2009) was the first to tell you the real reason why Ranbir split with Deepika; Ranbir was not discreet about his less-than-innocent encounters with other women then. Maybe he knows himself too well to commit to something as serious as marriage.