But my guess is there may be some "black magic" involved in the whole thing. Eclipse in India is a great time for tantriks. They do different types of kala jadu to keep spirits trapped and use it to do anything they wish. May be Shiv is a trapped spirit. Rajan was against Sharanya-Vyom love story at first. But now he desperately wants Sahranya now? He know very well that this may kill Vyom. Sharanya is like curse in Vyom's life. But he is ready to sacrifice/risk his only son's life. That means his target is Sharanya. I think may be he is trying to control Shiv. And to control him, he needs to control Sharnya. May be he somehow used Shiv's soul and sacrificed it to achieve some super power/money.
As after watching what happened to Vyom any father /mother would do what Vyom's mom kept trying. There must be some bigger plan behind all these than 'love'race between Shiv and Vyom. If this was only love...a man like Rajan would kill Sharnya first, then make Vyom lost his memory. So this is not "love game."