My boss keeps telling me (f) that im not supposed to work together with my coworker (f) anymore because we get along to well

We would still get our work done, but we would laugh and yeah just get along. We tried to work seperately but since we are from the same department, theres not really a way to not work as a team? And although we try to stay apart from each other as good as we can, whenever we stand somewhere together my boss makes a comment about us and how we are not supposed to work together. Its so ridiculous. Has this happened to someone before? How would you react?