The antonyms for the phrase "busts up" are "fixes," "mends," "reconciles," and "smooths over." While "busts up" typically means to break apart or ruin something, the antonyms refer to repairing or restoring relationships, situations, or items. "Fixes" implies repairing or correcting something that is broken or functioning poorly. "Mends" often refers to fixing relationships, such as mending a broken friendship. "Reconciles" suggests repairing a damaged relationship through forgiveness or compromise. "Smooths over" means to resolve a conflict or disagreement by calming tensions and finding a mutually agreeable solution.