Salman doesn't really quit. He's been constantly hosting since season 4. He just says that he'll quit but he doesn't.
Neither did Rubina actually take divorce. They were about to take but they didn't.
Yes, Gauahar did walk out and returned back. You could say that is thuk ke chatna. But Gauahar's situation was different imo. She was very emotional when she walked out and wasn't in the condition to take a logical decision.