The best part of being a writer is that everything is material.
It’s also the worst part.
I can recall getting in an argument with my wife, a real doozy that (thankfully) happens only once a decade or so. In the middle of a particularly nasty exchange, part of my brain disassociated and started commenting, “Ooh, this is good. You’ll need to remember it.”
Luckily, I had the good sense not to stop what I was doing and write it down.