Would dark matter absorb gravitational waves?

It is very difficult to detect gravitational waves because gravity is such a weak force. For the same reason though it's very difficult to dampen gravitational waves. We know that dark matter behaves similar to 'normal matter' for what its equation of state and coupling is concerned, so it won't be able to absorb gravitational waves any more efficiently, which is essentially not at all. (Also: The expression 'gravity waves' describes a phenomenon seen in cloud formation and has nothing to do with General Relativity as Google will tell you.)