The antonym for "breaking it up" could be "uniting," "consolidating," or "joining." Uniting refers to the act of bringing people or things together to form a whole, while consolidating implies the act of combining separate things into a unified entity. Joining, on the other hand, refers to the act of linking or connecting separate elements. In contrast, breaking things up could imply the separation of elements, leading to division or fragmentation. In certain contexts, antonyms for breaking it up could also include "maintaining," "preserving," or "protecting," which connote the act of safeguarding or keeping something intact.