Arjun realized that all the warriors on the battlefield ready to shed blood were none other than his own relatives, friends, and family. He was filled with remorse and fearful of performing his duty of fighting this war. The cause for these sentiments was his attachment towards his bodily relatives. He became forgetful of his spiritual existence, that he was not just the body. His affection for his bodily relatives had blinded his consciousness.
In the materialistic concept, we consider ourselves to be only the body, which is emotionally attached to all its bodily relatives. As this attachment is based on ignorance it carries with it the physical burdens of life like pain, sorrow, grief, and death. Only the death of the physical body can end these materialistic attachments. We are more than just the physical body; our eternal souls are beyond life and death. Tangled in the various attachments of the material world, we keep forgetting that the Supreme Lord is our only permanent relative. He is the Father, Mother, Friend, Master, and Beloved of our soul.