It's hard to forgive for Advay indeed!
I said this in another post. I'll say it again. Advay witnessed his parents death, a brutal death as a young child. Seeing his mother get burnt alive,his father get stabbed to death must have been so painful for him. These memories must have haunted him all his life. I can't even imagine the pain he must have gone through. He is scarred for life. Chandni his friend was partly if not completely responsible for his parents death. The reason he became an orphan, He also lost his brother his only close family after parents.It's only natural on Advay's part to hate Chandni. He lost his parents!