Why did Henry's friends keep the truth from the narrator for so long?

Henry's friends kept the truth from the narrator to protect him from the painful reality of his situation and to maintain a sense of normalcy in their relationship. They believed that revealing the truth would cause unnecessary distress and potentially drive a wedge between the narrator and Henry. Their intentions were likely rooted in loyalty and a desire to shield the narrator from emotional turmoil. Ultimately, their secrecy highlights the complexities of friendship and the challenges of confronting difficult truths.