...no, they aren't. The bigg 'tiff' is just a misunderstanding.
The rumours started when Karan didn't turn up for Aishwarya's father's funeral. But sources close to the actor confirmed it was because he was tied with new little babies, Yash and Roohi!
He also mentioned that Karan did go over and see Aishwarya and Abhishek at Lilavati hospital to show his support and love.
So, there you go. All smoke, no fire.