At least to me - Yash getting angry with Aarti for "causing" the fire which destroyed Arprita's memories is acceptable. I mean how may times in our lives when something bad happen, we always need someone to blame...You know it is seriously human tendency to make "logical" sense of anything that has befallen us and make correlations between certain actions of someone (or even our own actions) to understand what has happened. Initially he blamed himself for the fire and then he blamed Aarti after her "confession." Even him going into a rage after that was fine as he has always been potrayed as someone who is still having problems picking up the pieces after Arprita's death. Imagine all his memories of Arprita in Mumbai was destroyed - he was not gonna be rational and think ok, I still have my masoulem back in Bhopal. Even yest, it was further highlighted that the doctors think he needs some professional help to deal with his distress...
However, what did not make sense to me was that Aarti could not put two and two together and know that the reason behind Yash's anger was due to this! I mean this may not even be the reason for Yash's anger as we have not seen his POV but why was Aarti totally clueless and was even begging him to tell her what she did wrong...She should have guessed this could be the reason behind his anger and stop with the tears and I am clueless crap!