The antonyms for "joining up with" mostly involve the concept of distancing oneself or disconnecting from others. Some alternatives include: separating from, disconnecting from, breaking away from, detaching from, disassociating from, and disuniting from. These words suggest a sense of independence or isolation, where one prefers to be free from the influence or presence of others. It's important to note, however, that these antonyms do not necessarily imply negativity or hostility towards others. Sometimes, it is necessary to disconnect in order to pursue individual goals or maintain personal boundaries. Ultimately, the choice to join or not join with others depends on one's own perspective and priorities.