it was b/c of her he did it, but she never told him or maybe she we don't know! But from what I've heard she wasn't happy when he did it, so I'm guessing even she didn't know about it! And honestly, no one told Vivek to do this, he's a grown up he can make his own decisions. Also, Ash was kicked out of a lot of big budget projects too, all the Yash Raj films she was going to do went to Rani or Preity... Ash's career wasn't doing so well from 2003-2006. I mean she had Raincoat, Choker Bali, and Kajra Re, but not blockbusters. After Dhoom 2 and Guru things began to change! So even she had to face some problems career-wise!
it was because of her he did it, vivek said several times that he felt the need to 'protect her' and that everyone including her wanted him to do this, but she was smart that she didn't appear in the press conference!
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