The term 'BREAK UP LINES' refers to a type of joke or phrase used to end a romantic relationship. The crossword solution for this term is PARSE, which is a five-letter verb meaning to analyze or examine something in detail. This term is often used in the context of computer programming, where it is used to describe the process of breaking down a complex set of instructions into simpler parts. In the context of BREAK UP LINES, it can be used to describe the process of analyzing the words and phrases used to end a relationship.