V is out and out evil, pathetic. He is masochistic and loves to be miserable. He loves getting sympathy, claiming self righteousness and mahaanta. He always has excuses ready for everything - blame someone else, claim vaada, duty and how he's not understood.
If he cant move on from Sai, why enter into any marriage with another?! Is marriage a joke for him to fake/make into a compromise?! Is it fair to fake a happy marriage in front of his child when he has residual feelings for Sai. Is it fair to Sai if he gets rid of her memory from CN, marries the woman who ruined her life and violates her last wish. When Sai returns he will be ready with accusations for her but have no valid explanations to offer for his own behavior.
There is literally not one theory that can explain why he married pp even if its "fake" and not registered and not consummated yet.
Theories floating around are-
1. Vinu was found and pp by virtue of birthing him became "mother" so he was asked to marry pp because vinu was attached to her. Well he could have insisted that pp become kaku once he was older. Or he could have sacrificed and become kaka to his child by handing child to pp.
2. To facilitate adoption. He could have married another woman instead of pp or tried as a single parent or accepted that without Sai he cannot be blessed with parenthood. If Sai cant experience motherhood, his punishment is that he can't be father.
3. Mansi dying wish. - mansi should be most upset that pp was cheating her son until and even after death. MB was progressive and compassionate and wanted pp to move on but not with her husband's brother! And if she did also for some twisted reason, he should have refused! He made dying wish to KJ to care for Sai- didn't fulfil that. He violated his wife 's last wish of pp not being in CN. He could've said I'll take care that pp is settled without marriage etc. The least he can do after everything he's erred on , is to not repeat his mistakes. If he agrees that pp can be forgiven, then he should make her move on with someone else. How is it fair to marry pp and bind her to a loveless marriage if he's forgiven her.
4. Family pressure- same reasons as above- makes no sense!
5. Pp mentally ill or suicidal - she needed treatment then, not enabling her delusions.
6. Vinu needed a mother - he has seen enough single parent examples and he had the backing of full family too.
7. Vinu would ask for his mother when older- its better to tell him the truth that his mother is dead. Yes he won't have a mother and would miss that always but he would still have a large loving family. He should raise his child to face the harsh realities of life, celebrate and be grateful for the blessings instead of painting a fake picture of normalcy. How is it fair to show a loveless, fake happy marriage instead of telling him about Sai- hos mother.
So essentially for all the most common reasons cited for this marriage to pp - no explanation is even remotely enough to redeem V or for anyone to sympathize.
Are the audience supposed to pity him when he recalls Sai and looks "sad"while being married to pp?! We might have if he had stayed true to her and been single lifelong, regretted his behavior. If he truly still loves her, he would never even considered getting married to another. But he has done none of these things. He chose to get married to PP of all people. So there's no sympathy or redemption anymore.