I think when dadaji is explaining to nivi that she was supposed to marry sid, it will hit that she is falling for viren. She knows now but is still in denial. How could you not fall for this guy!!!!! what more can he do to persuade her?. Viren is the type who will not loose interest, but he did mention don't waste time in waiting. So come on nivi open your eyes look what a diamond you hve right next to you!!