Use this phrase to show detachment from an issue or to indicate that it's not your concern. She's decided to not bother her head about the rumors and focus on her work.
Pro Tip 2/3
Reduces Stress
It suggests that engaging in the matter would be unnecessary and stressful. Don't bother yourself about the lost keys—I have a spare.
Pro Tip 3/3
Not Your Duty
Implies something isn't your responsibility or within your control, so you shouldn't worry. The billing errors aren’t for you to fix; don't bother your head with it.