So I personally think Kesar justifying himself at all other odd times, was different from this instance - because all those other times, somewhere intuitively or subconsciously he was aware of a guilt in being ridiculously unfair to Gulaal - and part of his justifications were almost for his own self!
Here on the other hand - where Kesar has risen to such humility and maturity, it's all out his love and devotion to the cause called Gulaal that makes him justify his intentions which are no longer marked by anything but goodwill. And IMO, it should hurt the most to have to explain oneself, when you know your intentions are pure and well meaning as Kesar's in this case. A feat only he could manage, because when it was Gulaal's turn earlier, she miserably failed them both!
Jzee what I meant was that he had to explain out of habit, yes I agree with you that the accusations were far too disparaging and had he taken offence like she did and chose to walk away from there it will be completely out of character, he paid a heavy price for that internal turmoil when he chose to walk away and not confront her about what he had overheard at that stage,10 long years where he was searching for answers and when he did finally manage to gather that courage she let him down so badly….
I think you have said this somewhere before this basic difference stems out of their individual characteristic where both of them subject themselves to be responsible and answerable toward only one they love and that's why I think when he says that she is forgetting the relationship they shared beyond his love confession had died for her…even when she is trying to manao him in the kitchen he says the same thing…"Main tujpe apna haq samajta aaya hu bina koi rishte ki parwah kiye,jab se tu iss ghar main aayi thi…."
What I wanted to point out was that once he knew what selfless love meant he was so above these ego and resentments that he would have done anything that would make her happy,if that meant clarifying baseless accusations however hurting so be it….anyway this is how I will interpret his need to explain his stand after that mandir convo with terrorist….