Abhinav's logic -
He had said big things about how nikki spoiling the doll shows what she is as a person or not. Big boss gave a task where he had to wash the same doll and ghutno pe baithke woh doll nikki ko dete huye kehna tha ki nikki sahi thi aur woh galat. Aur yeh sab usse kisi aur ko bachane ke liye karna tha jisse woh apna kuch khaas acha dost nahi maanta tha....tab he dint felt that it was an attack on his self respect. And he shouldn't do it ....he dint felt that there is no need to sit in front of anyone on knees if he doesnt considers himself wrong. That time it was all about protecting kavita but today he feels that if he protects rahul for safeguarding himself......he will loose self respect.
He thought that he don't want rahul inside, so that rahul couldn't furthur misbehave with rubina (though rubina is very much capable of answering back but still, chalo he is her husband afterall ) but he dint thought that he is risking himself going out there.....if he goes outside and rahul is still inside, then toh he wouldn't even be there to protect rubina, atleast right now he comes in btw and fight for her which he feels is right. If he was so concerned about rubina, why dint he thought of this scenario that if he got eliminated instead ....then it will be rahul rubina inside and him outside. Atleast if he saved himself......he will be there for rubina.