Why because his heart is filled with pity. The word Hosea uses comes from the verb nakham which means to sigh. It is the sigh of the parent whose kids has done something stupid and dangerous. It is the sigh as you throw your arms around the child simultaneously relieved that they are safe, but still wanting to kill them for being so stupid.
Ben those of us who are well into the second half of life, can still all to often be foolish children. Sometimes we wander off the path because we a easily distracted. Other times we make a headstrong choice to go our own way. The good news is that God's love remains unchanged, he does not unleash his blazing anger. And you have to love the answer to the question why. Why doesn't God unleash anger?
For I am God and not man