The thing about eternity no one seems to realize is that it lasts an incredibly long time. Things with no definable beginning or end are funny that way. But at the same time, there are only so many things that can come into existence. Only so many variations of particles and matter and concepts and ideas.
Only so many destinies.
And, at some point in the unending history of the universe, it will run out of new things and will have to go back.
Wash. Rinse. Repeat.