Marriage is a huge commitment that is social as well as spiritual. The social aspect of it includes all that stuff we hear people talk about in the serial, including "kartavya", duty etc. However, the spiritual bond enjoyed between the couple is something that also needs addressing "legitimately"!
It may have been fine to have a script where such a 'switch" of bride goes unnoticed for some time. But it has gone on for too long. The script needs to resolve the legality of the marriage and proceed with the problems that would be faced by society and by the couple when the "switch" is indeed discovered.
There are several tracks that can be supported here that opens up several cans of worms, be they the abusive attitudes and hypocrisy of Amma, the cunning of Mrinalini, the future of Vishaka, the shock of Sastri ji and the ridicule he would have to face after the truth comes out, the confusion of Devki, the tenacity of Dadima, the worry of the stigma of social disapproval of Vaishali, the support of Birju and the transformation of Vivek from frustrated/depressed to one of being joyous and cured with maybe taming his wife and making her fall for him all over again! And of course the overcoming of each and every one of these by the "Rab ne banadi Jodi" of Dev and Rads!