First of all , trying to find logic in this show is absolute waste of time but since this was once a fav show and fav couple (n even now they are fav)...i thought maybe we could go into cvs mind and justify these recent changes in our Thahaan..
And is eriousy hope cvs would bring better plot and story.
Thapki POV
She always forgave Bihaan .( u can debate on this if you want to )
Whenever any close relation was in danger , she used to go hyper..
She wouldn't mind if someone is trying to hurt her but if anybody related to her is in danger then it's another story.
She was the one who justified a mother's blind love and her right over her baby , even if that meant it could destroy another's life. Like you can take the major incident ,where she forgave Vasu after knowing the reason behind the dhoka... She couldn't digest Kosi devi 's act because it would mean death to Bihaan even when Bihaan was her own Son...
So even if Thapki getting pregnant so fast was a major foolish act from the part of Cvs, her loosing the baby and her belief that it's because of Pandey people sounds okay to me and also due to Bihaan coz , according to her he should have read the letter and it's normal for her to expect him to reach out to her. ( u can again say that she could have called , or something)
Her hatred to Bihaan , yes could be termed as illogical coz her character was always for love and with love you can change people, but could you explain what should she then feel for him? and mind you , even in normal miscarriages mothers go crazy and this was an accident especially when she felt abandoned.
She fought all the way for him , but he never wanted to hear what she had to say, neither did he trust her when she needed that the most. But she did trust him even in bauji case and in Sapola case , she knew blindly that he could never do such things...( if you want to blame , please do it on the Cvs coz to glorify the FL they brought all these tracks, and butchered the ML ).
This revenge track , or the revenge that Vaani has come for, is just for show... coz in reality Vaani/Thapki won't be able to do it, coz she is already failing in it , making mistakes, and also when she would get to know that Bihaan didn't know and Kosi was behind it , more than Bihaan she is going to feel guilty ... because her wound is going to be filled with that love her husband and family is going to show..., and then she would realize that holding on to that wound is futile.. ( purely my guess, that's why i said in a way it's good that she is back for revenge , coz she can't ignore the love she would be showered on).
And for the look , i think even Thapki knows that Bihaan would identify her even in a beggar 's attire , this look is to fool Kosi devi and Shradha.
Bihaan POV...
I won't blame him for the rage he felt when Thapki accused his mom, but still he could have taken a deep breath and tried to find out both their point of views.. and he was the one who should have known that Thapki can never Kill anyone...okay let it be coz we all know how sensitive he is when it comes to matters related to his mother.
For him, everything is fault of Thapki, she accused his mother did all those bhoot drama and got herself in an accident leaving him alone..( guy , i wish you had listened what Thapki had to say)
The initial trust that he had for Thapki was i think erased by Cvs...
The way he abandoned Pandey people after knowing that Kosi is his mom, and all were acceptable but he himself not questioning his mother about the time that she took to come to him is a bit odd...
Poor guy doesn't know that he lost a beautiful reality , coz of his mom.
His rant that he hates Thapki is dhikhava... he couldn't digest she was dead so to express all those desperation , anger and maybe a little bit of guilt , he became a tapori...
He trusts what he sees and a man of emotions acts at the moment, 'think and act' is a taboo for him i guess...
Right now he is sure Vaani is Thapki and to prove it he is going to cross any limits , i wish he would only then Vaani aka Thapki can let herself be healed. ( i hope we get beautiful romantic scenes, but with those buck teeth ..i don't know..)
i just hope by the time he gets to know the truth Vaani would have shed her anger and would be there for him...
His behavior in the past is something i thoroughly hated , but now i pray that he succeeds in mellowing Vaani...coz that's necessary ...
In the end, i am sure Thahaan would heal each other's wound and would be back to being the lovey dovey couple...
And for all Thahaan shippers and Thapki viewers , i would say the plot would have been interesting and acceptable only if the cvs were not running a marathon and could have executed the scenes well. it would have made us relate to the leads emotions. so i would say blame the Cvs coz they are just pushing the story not narrating it to the audience.