If i was on gauri's place and God forbid IF Shahrukh ever ditch gauri for another woman.. i would do the samething as she had said! Gauri knows him for so long and she knows how desperately he loved her! and even after loving her like that still he seeks for another woman.... its a guilt u can never forgive. that's what she had meant. its not that she literally pray to God everyday like that! and also she must have hinted at KANK coz she mentioned 'Since its u Karan....' and after all they are the scandal-less pair ever in the film fraternity and loves eachother like nothing. and they know it!