I just have this very strong notion that killing Shivvay post marriage was always in the cards. Shivvay is not going to insist on the physical relationship after marriage of course and Tia knows that. So after a couple of weeks of marriage he is conveniently bumped off with a planned accident.
I mean, I don't have to spell it out that Tia then inherits his share/money etc and Tia being the young widow finds, after the appropriate mourning period completed, solace in the arms of their common friend - Daksh. That is if Daksh indeed is Tia's husband. I mean with so many attempts made on his life while Gayatri was in the picture no one will even suspect if Tia manages to 'bump him off' after marriage. I cannot see why the Oberoi's would object to Tia remarrying as they are very forward thinking people.
I know it is a silly thing to go by but when the blood fell on Shivvay's birth chart that is the first thing that came to my mind. His marriage to Tia will result in his death. Of course, I did not know then what Tia's motives were but the whole ominous tone with which the priest spoke was like a clue. So either it was a plan Tia and family made to set the stage for his accidental death (seeing how her partner manages to waltz in and out of the Oberoi mansion whenever he pleases) or it the bird did end up dead when it flew up there.
Shivvay on his part, in his personal life, is a very predictable man and that in my opinion is his major weakness which could have resulted in his downfall. His enemies can predict his reaction to every action that they make because he thinks with his head. Every move is logical and set. This is why he is being played like a pawn.
Tia and her accomplices bank on Shivvay being Shivvay Singh Oberoi not matter what because that is how he has always been. That is what Tia meant when she asked her mother"do you have a better option". Mr. SSO is a sitting duck that they can aim at anytime because he is predictable and easy to read.
Shivvay, I assume from what I am hearing about his marriage happening to Annika, breaks this habit of being predictable and that is what throws everyone in a tizzy. Suddenly they are scrambling for plan B that they never thought to make. It could be the reason Tia holds Shivvay to the promise of the merger even though he marries Annika. It ensures that he stays in touch with her and views her as a friend in the event of Annika's death, and believe me there are going to be attempts on her life if Tia needs to get back in. So even after Shivvika marriage Tia is still a family friend of the Oberoi's and continues to create MU between Annika and Shivvay.
lol... this was supposed to be a short post ... sorry everyone