Wait... it doesn't always have to ruin both. Sometimes the work part just gets wrecked. I hired a buddy once to help on a big job, and he was a no-show half the time. We almost didn't speak for a year. But we worked it out eventually... the friendship survived, barely. I just know I can't work with him again.
Seriously? I've never seen a work friendship go bad and bounce back fully. Once that trust breaks over money or deadlines, something always feels off. You just can't reset things like they were before.