  We explore the idea that the coupling between matter and spacetime is more
complex than the one originally envisioned by Einstein. We propose that such
coupling takes the form of a new fundamental tensor in the Einstein field
equations. We then show that the introduction of this tensor can account for
dark phenomenology in General Relativity, maintaining a weak field limit
compatible with standard Newtonian gravitation. The same paradigm can be
applied any other theory of gravitation. We show, as an example, that in the
context of conformal gravity a generalised coupling is able to solve
compatibility issues between the matter and the gravitational sector.
