from the time nachiket has returned he has numerous times told ragini how bad a wife ,mother ,woman etc etc she is ...he has mocked her ,insulted her and taunts her ...and now he went ahead and got engaged to nivedita...and pam painted the picture of a fairy tale and still nachiket let her do it...so for ragini nachiket is in love with nivedita and has moved on to the ideal partner he was seeking approved by his sister...even if the fake marriage is out i do not see ragini taking any step to ruin his happiness and life with nivedita as per her...hence something major has to occur for both to burst out about their feelings for each other...untill then they will be miserable but will suffer
Pam wouldn't have probably done so if she din't realise that R was faking her marriage. Once she knew the truth, she realised that she was sitting on a tinderbox, with Nivedita, and hence she did what she did. That idiot! And also because N allowed her to get away with all these.