She is protective of her sister . She knows noone will protect her if she loses hers .
In live feed
Jyotika also another chugal khor , nikki part 2.
Also
I wanna tell you something
Rubina keep telling her sister to stay quiet and they only have few more days to live with housemates.
Also
I saw Jyotika n Rubina into similar situations like she used to b with Abhinav.
Exactly she talks like this is not us bla bla bla where as when Nikki does so much wrong she hardly called her out clearly shows her connection is fake and for the game. If she was genuinely concerned for Nikki she would have given her genuine advice like how she gives her real sister.