User blog:Bardockslilbab/A completely different ending theory.

Remember the Arrival DLC? The Reapers plan to arrive through the Alpha Relay. We know Mass Relays are their method of invasion. However, we have no idea if the Reaper fleet attacking the galaxy in Mass Effect 3 is the ENTIRE REAPER FLEET. Therefore, the destruction of the mass relays is necessary to prevent the reapers, if there are any left in dark space, from invading again.

Yes, it is that simple.