In essence, Israel had become preoccupied with what God had given her, they attributed those gifts to the Baals, and their worship had become syncretistic as a result. Whatever forget
means, it is much more than Israel merely forgetting about God. Because of their devotion to the Baals, Israel had failed to worship God and keep the covenant he made with them.1
13 And I will punish her for the feast days of the Baals when she burned offerings to them and adorned herself with her ring and jewelry, and went after her lovers and forgot me, declares the LORD.