Song of Solomon 8:6 KJB
This verse, like all the whole book of Solomon, is not about eternal Love, but it is about the love between a husband and wife. In the eternal power of Love, death is not as strong as love. God proved that His Love happens to be much stronger than death when Christ conquered death. II Timothy 1:10; I Corinthians 15:26 (KJB). The love of a husband and wife for each other only lasts until death parts them. In that sense, death is as strong as love.
Many of the ideas and emotions that God creates can be used in good ways or bad ways. The Devil cannot create anything. He can only misuse God's good ideas and emotions by putting them into false combinations that are lies or can be used as lies. The emotion called "jealousy" can be used in a good way or a bad way. One of God's names is Jealous because He knows exactly how to guard His people, and sacrifice Himself for them, to save them from all sins and evil that will utterly destroy them. Exodus 34:14 (KJB). But the Devil can misuse jealousy by adding the good and useful idea to it called "excessive." Excessive jealousy can cause a husband or a wife to constantly accuse their spouse of unfaithfulness without any real evidence. This is a sin because it can cause such misery in a family that it breaks up a home. Excessive jealousy "is cruel as the grave" because it can cause the death of finite love.
Excessive jealousy, like all sins and evil, is like "coals of fire" that is very destructive. This happens to be the Devil's misuse of God's fiery power.
But God's fiery power is much stronger than the Devil's fiery power. In the end of the world, God will use His fiery power against evil to thoroughly purge His entire creation of all sins, evil, eternal death, and the Devil. II Peter 3:9-13 (KJB). God is "not willing that any should perish, but that all should come to repentance." II Peter 3:9 (KJB). Since God's Will cannot be thwarted, then God will save His entire, living human race that He has created in His image. Genesis 1:26-27 (KJB). This universal salvation is a promise from God. I Timothy 4:10; Revelation 21:5; Hebrews 2:9-18; II Timothy 1:10; I Corinthians 3:11-15; I Corinthians 4:5; Revelation 22:11-12 (KJB). God has two forms of salvation. God can save by His grace those who come to faith in Christ's sacrifice for them while they are still alive in the flesh. Matthew 26:28; John 5:24 (KJB). God can also use His fiery wrath against evil to save the rest of humanity with a lesser form of salvation when Christ comes to visit them in the end of the world. Revelation 5:11-14; Matthew 13:36-43; Luke 3:16-17; Luke 3:6; John 5:28-29 (KJB). God can never lose anything He has ever created, and His Love can never fail. Ecclesiastes 3:14; I Corinthians 13:8 (KJB).