Why would both high beams on my 2003 Grand Prix stop working at the same time doesn't one go out then the other?

If both high beams on your 2003 Grand Prix stopped working simultaneously, it could be due to a blown fuse or a malfunction in the high beam relay. Another possibility is a wiring issue, such as a short circuit or a loose connection that affects both bulbs. Additionally, if both bulbs were replaced at the same time, it's possible they both failed around the same period. Checking the fuse and relay, as well as inspecting the wiring, would be good first steps in diagnosing the problem.