I don't know how Ghum writers work (I mean, making Viru grey shade, i have my apprehensions from writing stand point)
But, if I had to write it, considering the time gaps and everything, it would be something like this:
Sai tells Virat that she has lost all reasons to love him and drives off. Viru is all crazy and mad and everything and in the morning, the first thing on news is news about SaiYa getting married.
In fb, they show Sai walking around the election rally park, all tired and Satya meeting her and congratulating her. Sai reminds him that he is her ex and Satya calms down. Sai tells him about the promise to Vinu (more like talks to herself) and says that she will break her promise to Virat for that promise. Satya jokes that if they get married, no promises are broken anf he can get his mother to relax. Sai considers it and they brush it off. But then they actually decide that screw this shit and decide to get married. But Sai knows that Virat will use Savi as last resort and ask Virat to bring her at the bridge with the excuse that they need to talk.
Back to present where Amba realizes that this is the girl that Bhavani's nephew proposed to infront of the whole world and isnt happy about it, thus repeating Sai's cycle of having a sasural with a matriarch who doesn't approve of her.
Doing a public announcement about the marriage is a way of Sai watching her back and making sure that Virat stops harresing her (like the final episode of made in heaven). The police force will clearly not want their DCP stalking a married woman, the Chawans have a reputation and Ninand and Omi will use that to get Virat to stay with Paakhi.