Looks like DK decided that he needed to split Sunita from Sandhya, and succeeded. His motives could have been anything, and Sunita could have been right - having seen how Yuvraj treated him, he may have decided that he needs an anti-Yuvraj ally, and if Sarla can betray Puru, she can betray DK.
He knows that he's irredeemable in Sandhya's eyes, and so it's safe for him to write her off. But by trying to grovel b4 her, he's at least managed to redeem himself b4 Sunita. That way, if he does have to do anything against Sandhya later, at least Sunita won't oppose him, like she did previously.
But I think the equations have changed both ways. Sarla thinks that DK stuck her up after she stuck out her neck for him and took so much punishment from Sandhya. Plus Sarla's main target is Yuvraj/Prabhavati, not Sandhya, whereas DK's main target is Sandhya. So while agreeing to DK's offer, Sarla is now probably playing games w/ DK and has quietly allied w/ Sandhya, since Sandhya is more interested than DK in sending Yuvraj & Prabhavati to jail. It's easier for her to get the property, particularly since the only reason Sandhya wants it is to prevent the Jagirdars from using it to cook evidence regarding their crimes.
After the Christmas episode, this week should be more interesting: the last few were rather dull.
Kyunki Saas Bhi Kabhi Bahu Thi 2
