The two sides of the coin run perfectly fine on their own. My point is that when we zoom into a large object, those atoms bonded together are not going to display quantum weirdness. If we separated a single atom from that object, I claim that atom has become 2D, but is 3D while we are observing it. So to unify, we can write an equation that says Relativity is 3D and QM is 2D or less.
Quantum field theory and Quantum Electrodynamics obviously haven't unified the two yet because we get guys like this still saying they are not unified, from a couple days ago (see the 3:10 mark) https://youtu.be/dW7J49UTns8?t=190