The EU won't tolerate a non existent border with a nation that doesn't share the same standards as them. This is true for all countries bordering the EU.You seem a bit confused.
Neither the DUP or the British government is advocating a hard border.
It is the Irish Government and the EU and who want their slice of the UK cake.
Expecting them to accept one in Ireland is just stupid. It was never going to happen. Everyone knew this.