0 If a relationship busts up, or the people in a relationship bust up, the relationship ends:
1 a serious argument, especially one that ends a relationship:
She had a big bust-up with her brother-in-law.
2 a serious argument or disagreement, especially one which ends a relationship:
We can complete it step by step however long the road is and it can't be completed however short the road is if you don't even mark your footprint.