I don't think Kareena had anything to say in Sara's life. Most of the time it looks like Sara doesn't take Kareena seriously.
I think Sushant didnt get along with most of the others because he had different interests. He didn't like gossip and was to nice to pull other actors down, etc. and wasnt interested to much in PR games and that's why he wasn't liked much by them. Unfortunately for him, he wasnt able to fake it to fit into these groups.
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