There is a broad differential diagnosis for headaches. Although a blood pressure 150/110 is considered hypertension (high blood pressure), a single measurement cannot diagnose hypertension and, at that measurement, it is unlikely to be the source of her headaches.
If her headaches do not improve with NSAIDs (Tylenol, ibuprofen) or she has fever, nausea, vomiting, diarrhea, altered mental status, blurry vision, then a detailed medical evaluation is warranted as without a physical exam, detailed history, and lab tests it is nearly impossible to diagnose your girlfriend.
