Night Classes

During work, Raman and Narayan were chatting:
Raman: Narain, I’ve been attending night classes for 5 months now and I have an exam next week.
Narayan: oh!
Raman: For example, do you know who is Graham Bell?
Narayan: No
Raman: He’s the inventor of the phone in 1876; if you take night Courses you would know this.
The next day, the same discussion took place:
Raman: Do you know who Alexander Dumas is?
Narayan: No
Raman: He’s the author of “The 3 Musketeers”, if you take night courses, you would know this.
The next day, once again:
Raman: And do you know who Jean Jacques Rousseau is?
Narayan: No
Raman: He’s the author of “Confessions”, if you take night courses, you would know this.
This time, Narayan got irritated and said: And you, do you know who is Balakrishnan Kuppuswamy?
Raman: No
Narayan: He’s the guy roaming with your wife!! If you stop night courses, you would know.