Person 1 and Person 2 are scientists in a dystopian future, working on an algorithm to create a way to travel between the infinite universes. They succeed.

Person 1, hopelessly in love with Person 2, figures this breakthrough would be the perfect time to finally confess. That's when things take a turn for the worse.

Instead of sending someone through the machine, someone else comes out of it. A very familiar someone. 

Alternative Universe Person 2 comes through, kidnapping Person 1, and takes them back to their universe.