They all shared a tragic experience and they all knew they all had to tread carefully considering the sensitive situation. Hari, despite knowing of the "future" she knows, is experiencing an entirely different timeline. She may be emotionally and mentally mature, but she's still under the shock...
When we begin to realize the contempt the brothers have against Hari started from their childhood, only brewing to become more severe in their adulthood, we'll see that there were reasons their "childish thinking" now takes on a different plane of abuse on the long run. Let's realize that...