Very nice post. Sorry that I missed it yesterday.
I too did realize that yesterday when he mentioned that it could be someone else the expressions on Rishi's face did not justify that he did this blunder by mistake. So far whenever Vidhit's name in conversation with Indira or even when she asked him when he would introduce her to his parents as he wants to help her by marrying, his transition from expression of surprise/shock to normal was very evident. This was not true yesterday. And for that moment I felt something is amiss. Your post clears that. I too agree with your reasoning. He is not in Sharma Niwas to fall for her. Possibly I know why he is here. He explained his motive to his brother, ex-gf and viewers ofcourse but in different way. Remember, he left a letter for his brother that he was back in India to close chapter with a girlfriend so that she can move ahead in life and get married. Though he said that work is done, we all know he said so to distract his brother from looking out for him. But in reality that is the reason why he is here. He wants Indira to move ahead in life, settle by getting married to a right person who will keep her happy.
After new party, when everyone in the forum felt that Indira has started to love Rishi, I felt that it was just the comfort level between two. They are comfortable with each other. Rishi has been flirting from day one. That's how he is. We can call this behavior of his as reckless, irresponsible.
But yesterday, he wanted to test Indira. Though his statement came only after dispersing the gathered crowd. So he did not insult her in public. Now it was the fault of her family that instead of trying to find the truth they built theory and concluded that it was Indira. This shows there desperation of controlling her and getting rid of her. When Kutumb questions Indira's character it is when I saw that guilt-ridden expression on Rishi's face in the back-ground. Only then he realised the seriousness of his casual saviour statement.
I must say, if Rati is doing a fab job of a smile-less, head strong girl; Sumit is no less. This guy is an amazing actor. His transitions to different expressions are just apt.