The current track of Yeh Hai Mohababtein has Ishita getting possessed by Shagun, who jumped off a building to commit suicide. It started with Ishita behaving like Shagun at occasions and eventually turning into her, full time.
Ishita will be seen screaming and threatening to hurt everyone around her. She even yelled at Ruhi for calling her Ishima and clarified she was Shagun. Santoshi, Madhavi and the others will then witness Ishita's behaviour for the first time.
Raman too witnesses Ishita's behaviour but when everyone insisted that they seek help for Ishita to deal with Shagun, he insisted that Ishita is fine and that she is not possessed and just needs help to deal with her stress.
The upcoming episode of Yeh Hai Mohabbatein will have Raman trying to feed Ishita and she pushing the food to behave like Shagun again. Raman, wo had been insisting she was just stressed, might change his opinion soon.