We are looking at everything completely wrongly.
Likely this. The (very successful) Standard Model is fundamentally a quantum mechanical model, and the only fundamental force it doesn't describe is gravity. So the obvious thing to do is try and find a quantum gravity theory, because all the other fundamental forces are quantized, so gravity should, intuitively, be quantized as well. But quantum gravity seems to be rather elusive, which is the main roadblock in physics atm.
But accepting the field-based General Relativity, while generally being very successful by itself, also has its issues. It leads to singularities and physicists don't like them, since it feels like shit went wrong somewhere.
So the hope was that quantum gravity would solve some issues there, but it remains elusive.
It's also not all that cool to have two fundamentally different sets of theories describing the universe, ideally you'd have one single theory describing all fundamental forces.
That's not what "Grand Unified Theory" means, btw, because even on the quantum field theory side there are still different theories going around. There's the Standard Model (electromagnetic and weak interaction), and Quantum Chromo Dynamics (strong interaction). Combining Standard Model and QCD would be the GUT, and a theory that would involve gravity would be a theory of everything.
/edit: Also, sorry for the weird terminology. Both Standard Model and Relativity are field theories, but I meant tensor field theories that are continuous when I talked about them earlier. Quantum Field Theory is a quantized field, not continuous.
