We have to accept one thing about this show . The lead characters have different priorities in life , even though they are in love , to them their priorities mean everything , even more than their own happiness.
Manav's priority ...is his family and his commitment towards Shravani . Not because of love but because he is a man of his words and it was his decision to marry her and he wants to make ammends for his brother's mistakes .He does not consider Archana his priority at all. He definitely loves her , but not enough to give her preference over his promise . His intentions about Shravani are absolute. As of now he has made up his mind that she is the one he will marry and make his family ( specially his mother ) happy again .
Archana's priority ....is Manav and Manav alone .Nothing is more important than him , not even her own happiness. She is doing what she is doing because she wants to show him that she respects his decision and will never mistrust him again , she made that mistake once , never again will she let that happen . If she is going through this terrible ordeal then the reason is to just make sure that Manav knows that she trusts him and how much she thinks of him . It is not to get him but to make sure that he too will trust her and somewhere in his heart think well of her . She is ready to sacrifice anything to have this .
Even today before breaking ties with her family , she looked at him and that is what gave her strength to say yes to savita's condition.