Do two walk together unless they have agreed? From God’s perspective, the imminent threat of destruction by Assyria that Israel was facing was not only unavoidable (“ a lion roars in the forest only when it has prey”), but was also “justified.” It was a fate that Israel had brought on her head and there was nothing the Lord could do about it. And this fact pained the Lord. Israel was the Lord’s beloved, the Lord’s chosen (“ You alone have I favored more than all the families of the earth”). God did not only raise Israel from among the tribes of the earth to be the Lord’s own. God also made Israel God’s “equal”/partner: “It is too little for you to remain my servant. I will make you my friend and a light to the nations” (cf. Isaiah 49:6). The two had agreed to walk together! 
As God’s partner and “equal,” God had shared God’s secrets with Israel, shown Israel the right path, made a pact with her, and entrusted Israel with obeying and remaining faithful to the terms of the pact. But through her actions, Israel forgot about God and the pact they had made. God felt betrayed by a friend and a partner. 
God did not send the prophet Amos to warn the Israelites. Rather, Amos was sent to let them know of what was coming. God did not want the sons and daughters of Israel to have doubts as to the origin of the impending calamity. God wanted them to know that God “allowed” the Assyrians to overrun their land. Perhaps this would serve as a lesson to them. Perhaps after the Assyrian invasion, Israel would be reconstituted and once again become the Lord’s beloved. Perhaps this was the only way Israel could meet their God and talk things out.