I do not think that his character has been ruined. Bhaan is a person who loves his family blindly and trust it completely.
Yes he is a keen observer and senses stuff but these days he is just too happy to get the love of his life and he can never think of his god like brother who has always been positive no matter wat he went through to suddenly become so negative. Plus he is always busy doing one thing or other so he is not giving much of a thought to wat is happening around him.Another of his week point is always blaming himself for watever wrong happens around him. So again Sapola is using this against him and now instead of realising the tru situation, Bihaan will feel that he lacks sthg and that is why Thapki is not sharing stuff with him.Any way lets c wat happens next as the track has now shifted from Thapola to Bihola 😛 for which I am thankful to God