For the past 7 yrs Anu & bajaj addresses each other as "Aap" and I have never heard Prerna calling him "Rishab". She always calls him Mr.Bajaj or Bajaj or same goes Anu and Even Bajaj never called his real name Anurag. They have always each other by the last names Mr. Basu and Mr. Bajaj.
It was unlike of Bajaj to talk to Anurag that" TUM NE meri biwi ki jan li hai"