The scene bt Gauri and Mahen seems to suggest that Mahen was not involved in the conspiracy. The pain in his voice and eyes made me cry....I didn't cry or feel upset at any other period in the episode.
Mahen seems to love Gauri as a daughter and the fact that he might have been even indirectly responsible for her possible death gives him a lot of agony.
The scene bt the two was one of the most emotional I've seen in a while...no I must include Dadi's pain the day before. That was heart rending to watch as well.
Compared to that, the two main culprits, Nikhila and Shiv come across as conniving and callous, esply Nikhila.
I think, like some others have already suggested, that Ekta's purposely turning Shiv character into an evil one so that we won't miss IQ once he leaves!
Plus, she won't have to replace him with someone new as we'll all hate Shiv by then. That way the challu madam will save on the cost of employing one more actor. Smart, nah???