Here is what I feel about the incident
1. Tejaswi- Someone tell her that Rajiv did not come because of her heart, he was hurt and just wanted to relieve his agony and she happened to be there. Also If Shamita is controlling others so is she, at least that appears to be the case.
2. Shamita- She needs to understand apart from feeling hurt, as to why Rajiv did not come to her and sort his problems out, instead she is attacking Karan as a defense strategy when he was simply suggesting to be more sympathetic towards Rajiv's feelings.
Additional point: A lot of times I have seen Shamita to be pissed off with Rajiv for not supporting team or point of view and supporting other like Pratik, naturally Rajiv at times might have felt restricted.
My final verdict is both are insecure to different levels in a case to case basis.