I don't fully agree with you. Abhinav always supported, defended and guided her. That's why Rahul even called him saasta vakeel and he was asked to stay out of Rubina's matter by Salman and the guests. There were times Rubina wouldn't listen to him and do stupid things. For example during the box task and she highly looked stupid. During the night drama she was right to take a stand for her sleep but she took it to another level when she mentioned the challengers as guest and would be kicked out soon. Then the entire gang ganged up and it looked like they were doing it on purpose. No wonder they were bashed. If Abhinav stopped her that time it was only so that she doesn't go wrong but as usual she didn't listen to him and got badly bashed by Salman. Now he should stop guiding her. She will make it look like he is using her.
About the Kavita issue, if she didn't want to question him then why suddenly bring it up now. Either both are using that thing to stay in the game or else Rubina is really pissed at him. I rather believe it's a strategy than Rubina throwing him under the bus. This will completely ruin her image.