this is a smile which appears on his face, when he heard Maanvi herself saying in a crystal clear voice that she is FINE and her journey was awesome.. she said it such that .. they will calm virat from thinking and worrying about her...her words were not for her jiju ..but for Virat where she was saying "Virat, I am FINE, and my journey was good and you don't worry about me" Virat's smile is only due to the mere presence of her voice.. and her assuring words that she is fine.. i think this is where he sensed that Maanvi knew he was standing next to his brother...and the words which he heard from Maanvi were direct words of assurance to him...

and here we have Virat smiling once again.. when Jeevika asked Viren to take care of Virat.. now Virat's belief that she knows about him standing next to his brother was quite clear.. these are the very words she said Viren when they were about to go start from Hrishikesh ... Maanvi said Viren "Take care of Virat" and when Virat comes to see her off.. she tells him the same line "to take care of himself" and now again Jeevika tells Viren to take care of Virat.. Virat knew these are the words of Maanvi .. as no one except her would tell Viren to take care of Virat...
Awww are we seeing Virat crossing fingers.. for a guy like virat ... crossing fingers and expecting something to happen is childish and illogical..but when it comes to love.. logic does not count .. you do every childish and illogical thing to hope and dream and chase your love...
when Viren said.. that everything will be fine and he will win his love...Virat has a hope and he crossed his fingers for the hope and dream not to be shattered , but to see the light of the day ...
