There is a fine line between loving someone for eternity and being obsessive about something...
Yash is being illusive... Even a twin sister of Arpita comes in front of him he should know that this is not Arpita as she is dead... Dead do not come back and dance and sing and get kissed... He went in to trance... he was hellucinating even his mom was surprised that what the heck Yash is doing??
Yash was soo happy to see his Arpita back to life that he kissed Aarti's hands... we have never seen him kissing Arpita's hands..
So he is being confused with imagination and reality and this kind of behavior falls under psychological disorders...
What I mean to say is that Yash is not that way. He is normal caring loving and noble person they should not show him going in the trance all the time he sees something similar to Arpita...
In the begining it was ok with Kangan and razore as they wanted to tell us how much Yash misses her even today..
But they really went over board when they brought Arpita from dead to talk to Yash in the garden under the moonlight... That was not memory it was illusions as Arpita came and said I came because you called me... oh really???? and that is a sickness as it is hallucination and not reality..
Remembering the past is ok so all the incidents where he remembers having fun with Arpita was ok but then talking in the moon light and dancing with Aarti thinking she is Arpita is his illusions and that is psychological disorders...
CVs really went over board making Yash think this way and then when his illusion was broken he was violently angry and shoved aarti away with ferocity of an angry bull.. that is sickness.. He was sooo angry that Punkaj needed all this strength to hold him back otherwise he would have pushed aarti to the wall or to the floor and may have injured her physically and that is sickness...
Yash is not sick he is just grieving... Yes he was angry at the lie Aarti spoke to his daughter and that anger was ok but viloence was not ok.. as all the children got scared by that and left with their parents...