Lord Krishna said: You are grieving for those who should not be grieved for at all. The spiritually wise grieve not for the living or the dead!
Krishna makes Arjuna introspect over his grief. Intelligence alone introspects. It can be on an act, emotion, thought or understanding. Outcome will be the same.
Grief is common. Everyone can reflect upon it. The first chapter is Vish¡da Yoga, grief yoga, for this reason. Grief, introspected over, will take one to the inner blissful Self, redressing grief for ever.
Krishna says: “Bheeshma and Drona do not grieve. Why then grieve over them? Are not war and its consequences alike for them and you? They have no delusion in this. Shed your delusion too, and be wise like them.”
The wise grieve not for the living or the dead. The dead ever outnumber the living. Life and death are mutual. If none dies, where will even ants crawl on this earth? What you need is right understanding.