Ephraim is used 6 times and Israel is used 3 times in this chapter. Same way the name of God, the Lord is used 5 times and God is used 4 times. A simple addition gives us the number 9 for each of Ephraim and the Lord. That is the first theme "the relationship between the Lord and Israel"!
Three times the words " the house of the Lord " is used in vs 4,6,15. When they reject the Lord, they also reject his prophets. Prophets are Prophets are rejected, ill-treated, insulted, sometimes killed as well. He uses pictures to describe the condition of Israel: grapes in desert, first ripe figs, glory flying away like a bird and blight afflicting a crop etc.