Antonyms for the phrase "joins up with" could include "separates from," "divides from," or "breaks away from." These antonyms imply a sense of distance or separation, rather than connection or union. Other antonyms for "joins up with" could include phrases like "dissociates from," "disengages from," or "detaches from," which all suggest a deliberate effort to distance oneself from a group or individual. In contrast, to "join up with" someone or something implies a desire to collaborate, cooperate, or become a part of a larger whole. By exploring antonyms for common phrases, we can deepen our understanding of the nuances of language and communication.