Okay guys, I just saw the episode this post is referring to. Living in the U.S. we are a week behind ! Judging from the looks of it, it appears that, Kabir had a change of heart when Zeenat asked Kabir if he and Zara slept together, which would nullify their divorce.
Kabir though he was unconscious, or ill, he knew for certain, nothing of that sort happened with them. Along with the railway incident, when Zara was asked if anything had happened, Kabir was earnestly observing what her response would be. If Zara wanted she could have lied and said, yes.. and saved her marriage. But, instead of doing that, she spoke to the truth ! She denied anything happening between them, to nullify the divorce. Her answer was kinda a 'make-or-break' for Kabir, and almost a test from him... he wanted to know what she says and or does.
She stood by the truth, and this is where she earned respect in Kabir's eyes ! He realized her importance, and especially when she decided to go away, handing him over to his mom, at her care, it kinda sorta 'woke' him up and he realized her importance in his life. and to be bluntly honest, somewhere along the lines, it did hurt his ego!
Till now, Zara was kind of like a puppy trying to stick by him and stay by him no matter what.. but after the incident at his project launch, she realized, she cannot depend on Kabir for his love and support, and that all her dreams and hope kinda shattered, because of how he treated her and her family, by not standing up for them. It gave her a reality check.
If Zara wanted, she could have prolonged her anger and resentfulness, however, she saw how sorry Kabir was, and how willing he was being to make it work. To her it felt, they were finally in the same boat ! Especially after Imran told her to give him a chance, she relented.
So its, really the 'turn of events' and 'circumstances' that lead to a change of heart from both sides.. for them to again, unite back together!
Kabir always had feelings for her, but his ego would be coming in the way of it. Which is why he never opened himself to her, fully, even though Zara did everything from her side !
But now, he is finally learning to see the truth, and Zara, for herself, beyond his ego and curtain ! :) .
Hope this explanation made sense ! ^_^