Although we see that Rajiv is pretending memory loss and all to help Divya.. but so far I haven't see any real help from him.. I mean after his recurence after the so-called death. Of course he was the one who helped them get married in the first place and also endangered his life for the same.
But now, he is only risking his secret to be found out by Chandra. Moreover, even if Chandra tells him something about Sin's plans, it is only after everything has already been plotted and he is not able to stop Sindura's plans anyway. Divya is already in trouble whenever he approaches her to tell that to her.
May be this time he will be able to tell Divya that this sudden appearance of Viren was also one of Sin's plans (which I don't think Divz has guessed yet) and then Divz might be able to help herself out somehow.. don't know how though...