So here's what's new with Fringe!

Olivia and Peter:

So Bolivia ( the fake olivia) came into our universe and her and Peter started a relationship and Peter did not know this was the wrong Olivia. Later Bolivia's cover was broken, and had to get back to her universe. Which she did. And at that time, the real olivia came back.
So for a while there was awkward moments between Olivia and Peter, and Olivia was upset that Peter didn't realize that was the wrong olivia. After a few episodes Olivia cools down, and things kinda get back to normal. But Olivia is still upset of how much the Bolivia ruined her life.

The machine:
This is a weird machine no less! So the only person who can control it os Peter. And as last episode we found out that which ever Olivia Peter likes more, that's who's universe will live.
Because আপনি also found out that Peter still has feelings for Bolivia.
So there's a problem in the future.