a) his mother died before his father, and he remarried.
b) his parents were divorced and his father remarried.
From the day where he described his affair with Neeru, and about how he asked her to move to his place, I have got the clear vibes that he is a textbook loner. I see a lot of such people in my business and usually they carry ovesized mental and emotional baggage, and end up becoming fairly dysfunctional and self-destructive. I am convinced that other than the obsessive Kashmira, Amit is most driven by the reward money to win.
I don't know anything about Rahul and cannot gauge that guy. But Ravi and most of the others have steady and stable careers so win or loose they are in it as far as they can go.