When we turn that two-part verb into a noun (the breakup) or an adjective (the breakup process), we write it as either hyphenated or as one word. A good dictionary shows which.
Verb: It runs on. Noun: That's a run-on. Adjective: a run-on sentence
Verb: I am paid up. Noun: [not a noun] Adjective: a paid-up account
Verb: I put it on. Noun: It's a put-on, a joke. Adjective: a put-on accent
Verb: I pick it up. Noun: An 8:00 pickup Adjective: a pickup game
Verb: I'll take off. Noun: The plane's takeoff Adjective: a takeoff delay
Verb: You set it up. Noun: Directions for setup Adjective: a setup deadline
Verb: Look out! Noun: He's our lookout. Adjective: the lookout perch
Verb: Pay off the loan. Noun: Here's the payoff. Adjective: the payoff amount
Verb: I run away. Noun: He's a runaway. Adjective: runaway inflation
Verb: I run away. Noun: He's a runaway. Adjective: runaway inflation