Vanya have no depth

Vanraj was very clear that his relationship with Kavya wasn't a mere lust-driven affair. They legit fell in love with each other.

AnuRaj have 25-year-long marriage, sure. Vanya too have a 9-year-old foundation. They spent whole working days together for a decade. But still their relationship has no depth? They can't read each other's faces. Have no idea of each other's strengths & weaknesses. Heck, they can't even manipulate each other properly. How weird is that? We have deeper relationships with our college friends than Vanya have with each other!

i think its probably because their '9 long years' was the honeymoon period of their relationship. the thrill of going behind everyone's backs, the 'stolen' moments, and the fact that they were giving each other their best, because they were giving their spouses their worst (like anger, resentment, etc) meant that they likely only shared happy moments together, or they bonded over shared mutual hatred for each other's spouses. 

now they actually have to plan a life together, discuss deeper issues than 'when is our next hookup' or 'why i hate anupama' or 'you're so much better than my wife' or house issues and issues with kids. plus, with vanraj being the boss, he was richer and financially secure and could splurge on kavya.

just goes to show, conflict is what builds relationships.