Ishaan is an extremist apart from his selective chauvinism. He has severe abandonment trauma. Reason kuch bhi ho, he cannot handle being left or abandoned. We can see it in his regular bouts of venom he spews at Isha. We saw it when Reeva was leaving for London. And we will see it now also when Savi plans to leave his institute. See his Bhos-diwale institute is a direct reflection of Ishaan himself. When he has realized that she is an extremely bright academic prodigy he will not let her leave. As the promo suggests he wants to be her "humrahi" or partner, companion.
Now the relationship will move away from Isha being the reason Savi is there to Savi being a brilliant student and he just wants to encourage her progress. But I severely doubt his professionalism. He doesn't appreciate the fact that Savi is too independent and doesn't really need his support. After all this also Savi won't really trust or depend on him. Savi will take help from a Shuklaji or a Isha, or a Shantanu or a Bajirao, but not from him.
His efforts to support her will not get the desired outcome as I am not sure Savi will actually want or need it. And then the lines between being a professor and being a companion will begin to blur for him. Random nonsense pe he will display his possessive nature, stemming out of insecurity or fear. Knowing the storyline, Savi will actually look for reasons to stay away from Ishaan, and Ishaan will not stay away. As long as Savi doesn't assure him that she isn't the types to abandon him, like Isha or Reeva, he will continue this way.