The Israelites had taken the Covenantal promise and the language of separation and interpreted them to mean the message of salvation and restoration was meant for only them. But this is counter to the reality of the Scriptures.
The full effect of the Law had been visited upon God's people, but now the LORD will remember His people and return them to the land of promise and to Holy Jerusalem.
God will establish justice and righteousness even in the midst of the most uncertain and evil times. This we know because of the hope based upon the promise.
Man and woman together are complete. Apart, they are incomplete. The two correspond and form “one flesh” when combined in sexual relationships and as helpmates.
This complaining is a rejection of the LORD and all He has done to rescue them, guide them, and provide for them as He leads them to the Promised Land.