Koolsadhu I'm not saying that Archana was at fault. I think she was very human that day when she signed the papers.
Here we are talking of impulsive decisions- Archana had told Manav that she wanted to ask some questions before signing the divorce. After that she would sign.
But when the events took place at the chawl- she got really pissed off. She thought Manav had deliberately called her there to insult her. (Wrong). She thought he had stayed quiet while Savita had insulted her (Wrong- by the time he came Savita had stopped shouting). And finally she thought Manav doubted her character (Again wrong- Manav thought she had lost hope in their marriage and wanted to marry another guy and move on in life and not that she was cheating him or something- difference in both the things- the way he said it and the situations brought out the meaning of his words differently). It was very very natural of her to get flared up, and in that moment she took the impulsive decision of signing the papers and throwing them on his face. At that time she forgot about her earlier resolve of discussing with him first.
What I'm trying to say is, she was not wrong, but she was impulsive-it is human nature. Tomorrow when Manav says No to divorce bcos of something that Shravani does- then he will also not be wrong but will be impulsive.