I think Urmila's plan is working on Aham, he thinks she is going mad...his already said it when she was reciting the mantras in the middle of the night and pacing, he told her are you mad and went into the bathroom.
Her phoning him at work out of the blue with no explanation, are you okay, asking him, this is odd, when seeing him, reaching for his hand are you okay several times, when she thought he transformed from a chicken into human again.
Her shouting and crying outside alone, when he ran out to the garden and it started raining, that was odd to him, as no explanation was given for this behaviour.
Until he knows about the bhoot, he is thinking she has gone mad and doesn't know how to play it, if he yells at her, the effects of her madness might become worse, so his trying to just observe and not scream, as he thinks she is mentally ill and can't help this odd behaviour.
So I don't buy into the fact his changing because his suddenly in love, no its' fear of the unknown.