Raghav have seeing his worst nightmares resurfing again, his loved ones leaving him for he having flaws, he not being good enough for them, not worthy of them.
So the first escape route is lying, he is in desperate times. So hence keep making mistakes which are easy escape routes, but he fails to see this are short span happiness.
But he has never lied anything on personal level, he gas comes clean on that. It's just his profession, his business ways, that he now are biting him. If previously, when he was alone, he had no fear such, even though his ways were wrong, but again it never harm anyone.
Now he is also familyman, he never knew he would fall in love with such depth that with love, also comes fear of losing the person. It's not he doesn't trust his love, but he still feels unworthy of that love, with his past, hence he always keeps his loved ones close to him, tightly.
He just needs to have the confidence in his love and come clean. He breaking promises to Pallavi will shatter her, he is in desperate mode, he just needs the assurance from Pallavi that she will never leave him no matter what.
But I'm.not liking the way makers are making Raghav like a criminal, a Pallavi a mahanta ki murat. If it's clash of ideologies, could have done in form of challenge, not tagging someone as murderer and the wife getting to know things from other sources , without knowing how much the husband tried to prevent such circumstances to arise.