For some reason, the urge to wash that man (or woman) right out of your hair can also involve cutting or coloring your hair or getting a new shade of lipstick. Whatever it is you do, sometimes you need a breakover (breakup makeover).
Perhaps, you're declaring that you are a new person without the dead weight and splitting with your split ends symbolically represents that. The key, I would imagine, is to keep your breakover minimal. If that shade of neon orange on your lips isn't quite you, you can always rub it off and return to red. Blond skunk stripes? Not so much.
Have you ever gotten a breakover? What did you do?