Over the next decade, third-generation interferometers and the space-based LISA mission will observe binaries in galactic centers involving supermassive black holes with millions of solar masses. However, at the galactic scale, accretion disks, dark matter halos, and dense populations of compact objects can interact gravitationally with coalescing bodies. The role these astrophysical structures play in the evolution and gravitational-wave signature of binary systems remains largely unexplored and previous studies have often relied on ad-hoc Newtonian approximations. In this talk, we will discuss some recent improvements to this picture. In particular, we will discuss a fully-relativistic framework capable of studying gravitational wave emission in non-vacuum environments. We will apply it to galactic black-hole binaries surrounded by dark matter environments and observe the conversion between matter and gravitational waves. This coupling results in significant changes in the energy flux emitted, which could help constrain the properties of galactic matter distributions.