I understand what you are saying. We know one obvious answer. But that alone is not the reason.
Also, as much as there are additional scenes of Pakhi and Virat, there have been additional scenes of Virat and Sai too. Like the chocolate feeding scene on the first day of her college, the video call scene, the Naag Nadi episode, the hospital scene, the gift scene, the valentines day scene, the holi ofcourse and so much more.
They have given more background in Ghum for many scenes than in KD or Tamil.
In KD, the jealousy scene of Virat was limited to only one episode, here they showed us, him thinking about it the next day and visiting college too. Aniket track was a new track. And so was the hospital one.
I think they have always wanted to show his detachment from Pakhi and attachment to Sai.
In the Alta episode, the terrace scene made sense because Virat got to know what was Pakhi feeling. In other versions, they don't get to know like this. This is all a base for Pakhi's actions in future.
The ice scene wasn't necessary but Sai is very different from Emon or Saranya. We see Sai thinking about her feelings in Ghum whereas in other versions, they hardly do. For Sai to think about her feelings, I think they wanted to add jealousy as an emotion. This jealousy was expressed to Virat on the day she danced.
The same was with the rose scene. There was anyway no V day celebration in other versions. They want to show a contrast in Virat's behavior. The way he behaves with Sai and with Pakhi.
The Jhoola scene, though need not have been shot there, also showed that Virat trused Sai even after he had an argument with Sai right before he left the room. Pakhi's manipulation didn't work and she also got to know his trust on Sai. Virat shared what he thinks about Sai.
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