Covenant reveals much about God's personality.
To make a covenant with someone reveals much about your commitment level with the person you entered into covenant with. Covenants can only be entered into as a conscience act of your will, knowing exactly what you are doing and the ramifications of your actions. It is an extremely intentional act. It is a relationship of the highest order, not to be entered into lightly and treated as an insignificant matter.
Why was God so mad (angry)?
In the Old Testament we see God at times very upset with His covenant people. I was, for a very long time, rather uncertain of what to make of the anger of God. When I began to learn about covenant, and what that means as far as the relationships between individuals it creates, the anger became very understandable.
God gave His people Himself!
For the nation of Israel to walk away from God was act of betrayal. It is on the same level as when married couples betray one another. In that context the anger of God is understandable, yet at the same time we also see God ready to forgive and restore the relationship.
A love like this must be honored!
God gave His Son for us, and He is totally committed to us. This is the most important and the most telling fact about covenant. God makes and keeps covenant. He is diligent, compassionate, committed and an ever present help in the time of need. God has covenanted to us to be our strength. He is committed to be our strength! God is not put off by our weakness. He is moved by it. How moved? Moved enough to make a covenant and give us Himself!
"Finally, be strong in the Lord and in the strength of His might."