Govind seems to be like a father figure to Nandini.....
I think Sonakshi has a brother, Krushna's BIL. He was mentioned earlier but not seen yet.
Govind blames Krushna for something sinister and hence treats him like dirt.
Could it be that Krushna knew and will not reveal the identity or will not testify against his BIL to reap the benefits of being an SIL of a rich family?
Krushna has some obligation to Sonakshi's family?
Someone is holding something over Krushna's head and has bought his silence?
I have no clue, but it has to be someone known to the families. Aayi is just an irritating red herring in the drama...