Judges 8:33-34 And it came to pass, as soon as Gideon was dead, that the children of Israel turned again, ant went a whoring after Baalim, and made Baal-berth their god. And the children of Israel remembered not the Lord their God, who delivered them out of the hands of all their enemies on every side.
Typically, when the people’s spiritual (and military) leader died, they turned again and went a whoring after Baal and the pagan gods of the world. They responded to the temptations of the world around them and did not remember (worship and be wholly devoted to) the Lord who delivered them. They were unfaithful (using the marriage metaphor) because they had no shepherd to lead them. Israel was like all sinners in that they wanted to remain married to God while at the same time enjoying the pleasures of the world. Adultery kills by opening one up to the enemy. Without the inner restraints of faithful servant leaders people drift away.
The examples from the period of the judges shows us how important it is to be under faithful spiritual leadership and attend church worship regularly. The dangers from our spiritual enemies and the temptations of the world are too powerful to resist on our own without remembrance of deliverance and constant reminders of the Gospel. For this reason, God sends judges into our lives to preach the gospel to bring us to God and keep us in Him. Trying to go it alone does not work very well. The gods of this world are not friends of ours and will bring us into shame and misery. Look to Jesus daily (and only) for deliverance.