I have always wondered about it. I dont know how his brain is wired, so can someone explain this to me please?
DM knew that Anamika was a fake and still hid the fact from Santu, making her cry buckets wondering about her own place in his life after the return of his dead wife (as she thought Anamika was). After much heartache Santu gets to know the truth at the very end, along with the rest of the clan. She never got the privilege of being privy to DM's grand plan before he panned it out for the world. Shouldn't he have confided in his wife and put her mind at ease? (as he believes that husband and wife should not have any secrets between them)
Did he think she cannot keep a secret? If he did, then Santu is perfectly justified in safeguarding the secret of her sis-in-law, just to prove him wrong. Jokes apart, by hiding the truth from Santu, DM had harmed her more. Oh yes, he asked her forgiveness and was also willing to be punished but the guy must know by now his chokri will forgive him anything and will not dream of punishing him.
Compare DM's secret to Santu's secret. Here she was protecting the honour of her sis-in-law and also keeping her hubby from sorrowing over the loss of his son. By not knowing the truth, DM's happiness or peace has not been compromised, unlike Santu's case where her ignorance of Anamika's true identity cost her her peace and happiness. Granted it was for a short time but she did have to suffer quite a lot and over exercise her tear glands in the meantime. Now comes a time for him to forgive her but is he willing to reciprocate the goodness he was a beneficiary of? No.
So my question is, what really constitutes justice for DM? To me, DM hid something from Santu and Santu hid something from DM. I would say they are quits now.