We live in present, remember past, imagine future. This three consists our journey in life. Handling these three times together makes our life. All can't handle these three times carefully. This makes the difference in their lives.
Sameer and Naina when was telling their past of lovestory, then chachaji was dreading about their future. He decided to be with them at present however dreadful the future will be, if only his kids does not break his trust and stay in limit.
Sameer and Naina beamed in joy with the happiness of present acceptance of their love. At past Naina used to be worried about future, thinking that she won't be able to stand for her love in front of family. Now she got her chachaji by her side, so she happily started to dream her future with Sameer.
There Sameer though happy initially, he could not continue to dream about future, the reminder from Munna about the past break-ups and fear of dreadful future made him uncomfortable again. He could not enjoy the happiness of present. So, he shared this fear with Naina, while Naina looks at him shocked at this confession of fear.
All Naina need to do is to assure Sameer that, yes she will be there with Sameer too however difficult the future will be. Only chachaji's assurance will not work. Her dependence on chachaji only will not work. She needs to believe in herself first so that she can say that, yes she can stand the storm of life with Sameer ahead.
Same goes for our lives too. We need to believe in ourselves first, so that we can face the storm of life ahead. Dependency on others only will make us weak forever.