Actually past belief is the galaxaies are being held together and that matter according to gravitational theory should be holding the spiral arms together. This is the primary reason for Dark matter to explain this.
If the galaxies are actually flinging apart then dark Matter can't be holding it toegther.
The recent post of massive number or Red Dwarfs could be slowing this flinging as well.
Could this be the total demise of Dark Matter or will it continue.
Disclaimer
just a laugh