To forsake something is to abandon or desert somebody or something. God the Father had never forsaken the Son before. However, here in the agony of the Lord Jesus Christ, He cries out these words. Why has God forsaken His only begotten Son? It is for us so that we may able to return to God.
Matt.27.46And about the ninth hour Jesus cried with a loud voice, saying, Eli, Eli, lama sabachthani? that is to say, My God, my God, why hast thou forsaken me?