Pakhi in front of the sacred ceremonial fire, ink, and paper was wedded to Anshuman. She wedded him twice not once.
The first time she wedded him - she was not aware of the true meaning of marriage and perhaps considered him no more than a one-time visitor to her house.
However, in the interim between her first and second marriage - her mind was most likely shaped with all kinds of definitions of marriage, all kinds of expected behavior from her with respect to remaining single and faithful to him until he came and claimed her, all kinds of stories of the Dhola Maru type when he jilted her and married another woman (Ayaan's mother), and all kinds of sati stories after his marriage to Ayaan's mother.
However the most significant ideas and stories that shaped her mind and thinking were her own fantasies that were built on all the ideas fed to her. As a teenager she most likely fantasized about the ideal love she shared with a fantasy man (who because of her child-marriage) was named Anshuman.
She continued to live with her fantasy man in a fantasized married life by likening it to that of Dhola Maru after his marriage to Ayaan's mother.
When he still did not come and claim her after Ayaan's mother's death , she was a bit shaken but continued to live a fantasized married life with her fantasy Anshuman - for she did not have the courage to break away from her own self-built fantasy walls and accept that the real-life Anshuman was rejecting her.
When the real-life Anshuman married her the second time with the sole purpose of divorcing and getting rid of all ties with her - Pakhi was in euphoria because one tiny piece of her fantasy was fulfilled, in that the real-life Anshuman came and claimed her.
She lived in denial that he hated her, openly cheated on her, and colluded with one-and-all (including his son) to get rid of her. Her need to live her fantasy was so strong, that she put up with all his character defects and tried to mold him to, at the very least, accept her. It is to be noted, she did all of these to fulfill her fantasy, not out of love for the real-life Anshuman - for Pakhi truly loved her fantasized man named Anshuman.
She ran away from the real-life Anshuman when he questioned her fidelity because only she knew the depths of her loyalty to the fantasized Anshuman. When Anshuman got her back - she again, began remolding him and their life to fulfill her fantasies. Unfortunately, he did not live long and died in an accident.
She chose to marry Veer out of love and loyalty to (the fantasized) Anshuman's mother. She cornered Veer to marry by declaring in front of Ayaan her choice of husband and indicating that Veer is the best father Ayaan could have. Veer, who did not want to marry Pakhi was forced into the marriage by Ayaan, Pakhi's brother, and Girish who were witness to Pakhi's declaration.
Now Veer has divorced her. He has realized that Pakhi is still in love with her fantasy Anshuman. He knows the impact of fantasized love on one's mind - he went through it with Kirti.
However he does not know the depth and extent to which Pakhi lives in a fantasized world. Her conversations with Lavanya indicate that it almost borders a neurotic level.
Irrespective, Veer by giving her the divorce and walking out of Rathore Mansion, has given her the best antidote. The opportunity to find a healthy outlet and get over her grief.
Veer left Rhea behind to help Ayaan and make sure Pakhi does not slip into severe depression. Veer will help her take care of the Rathore business until she feels mentally equipped to do so. Veer is too self-effacing to say "I am doing this Pakhi for your good and out of concern for Ayaan", so couches it in term where he requests her an opportunity to be of service to her.
Pakhi's true test comes now - is she capable of self growth? Is she capable of breaking free from a fantasized man that she loved for over 25 years of her life? Will she turn into a neurotic or will she discipline her mind to face reality? This is the choice that seeks her immediate attention.
Veer by freeing Pakhi is giving her the freedom to grow independently as she chooses.