In Hosea, we see that sin isn't just breaking random laws. It's betraying a relationship. Hosea is told to marry a prostitute to illustrate that we have committed adultery against God.
So what is God going to do? Through Hosea, God tells the people that because of their adultery, He is going to act. And it's going to be serious.
He tells them:
- sins will be punished (ch9), judgement is coming, discipline is coming, wrath is coming (5), destruction is coming (7), they will be destroyed (8)
- their altars and high places will be destroyed (10), they think they are strong but God will make them like mist/chaff/smoke (13)
- God will rip them up/devour them like a lion/bear/leopard/beast
- the threshing floor and wine vat will not feed them, their food will be unclean, they wont remain in the land (9)
- no glory - no children, miscarrying wombs and dry breasts (9)
- their deeds do not permit them to return to God (5) and God will frustrate them and uncover their adultery (2)
- God hates them (9)
None of this is a surprise. Imagine the hurt and pain you would feel if your spouse committed adultery, repeatedly. The surprise is the reason why God does it. We would do it for payback, revenge, to hurt the other person, to make them feel some of the pain we have felt. That is not the reason why God is going to do all those things we've just mentioned.
The reason why God is doing all of that is to bring them back to him.