couple up
To form a pair with someone else. The phrase is often but not always used to describe romantic relationships. When the teacher told us that we could work with a classmate on the assignment, I immediately coupled up with my best friend. I feel lonely because all of my friends are coupled up and dating right now.
couple up (with someone)
[for one person] to join another person to form a pair. I decided to couple up with Larry. Larry and I coupled up with each other. By midnight, they all had coupled up and were dancing.