You're absolutely right. Bihaan's love is pure. His mind hates her but his heart loves her too much to see her in any problem. His trust has not wavered even after her deceit, he knows that Thapki cannot do something as big as mistaking paint for milk (regarding yesterday's ep), he'll give her his jacket to keep her warm in the cold storage (upcoming), etc. I know Thapki will also fall in love with him, if she's not already on that path but I don't really think that she'll love him the way he loves her. Whatever happens, for me, Bihaan's love will always be superior, be it only by 0.1%.