It is not a spat. This dispute has a direction of sorts. This means that the inhabitants of the earth have offended Yahweh, and therefore the dispute. This idiom makes it clear that the dispute is the fault of the earthlings. Hosea describes the foundation of God's dispute in three parallel statements.
EN is the particle of negation.
It can be translated 'nothing', but when it is in the construct state, it is translated, 'there is no'. This comes as a stronger negation than 'LO'. It shows a pretty absolute state of nothingness. The object of the negation is 'emeth, which should be translated 'faithfulness'. This is often used to describe the Divine Temperament, but here it applies to Israel.