Why didn't Harish and Preeti say that it was some third person responsible for Preeti's condition and Harish was just helping her without naming anyone? Isn't this a simple solution?
Why name him? Cheating lovers are not new things.
Even if you give his name - Kailash, fine! Avantika will be satisfied knowing that (she better be).
Even if you give his full name - Kailash Gupta. there are lakhs of Guptas in India. Other than Shilamami, no one will think in their dream about he being from Pankhuri's family. Pankhuri's family need not be informed, as it is private matter of Diwans. If they are informed, they will be quick to jump to conclusions, but they can be managed. Again, there will be hundreds of Kailash Guptas, may be even thousands,
Now, it is a separate matter that Harish (not Preeti) has given so importance to this matter that now Avantika won't buy even the truth. Because, she has been lead to believe that it can only be some matter of life and death that Harish would hide such a fact.
Harish has unnecessarily complicated this matter. If he had simply said that there was some guy involved on the anniversary day itself, whole drama could have been avoided. Avantika mollified. Pankhuri safe. Shilamami curious (nothing new here. She must have been a cat in past life. She surely is as stealthy as a cat. Sure has nine lives. Likes to live comfortable life without doing anything. And curiosity doesn't kill this cat at all. I am digressing...)
And, yes, he would have been lying. Preeti would have been lying. But, if a lie improved so many lives, it can live at least for a while.
Oh..yes..truth could have come out some other day, but its impact would have been quite less. Harish-Avantika relationship would have been stronger. Pankhuri-Avantika relationship would have been better. Guptas-Avantika would have been cordial.
Kya Harish! Khamkhan... complicated everyone's life!