Or Sergey Brin & Amanda Rosenberg, or Larry Page and Marissa Mayer.
That said, in all three of those cases they were dating an indirect report. That's still a bit of a no-no, but nowhere near as problematic as dating a direct report. Your manager has a huge influence on your career; the company CEO dating someone who works for the company is a little dodgy and will cause morale problems elsewhere, but it's much harder to argue direct influence when they don't directly interact in the course of the workday.
That said, in all three of those cases they were dating an indirect report. That's still a bit of a no-no, but nowhere near as problematic as dating a direct report. Your manager has a huge influence on your career; the company CEO dating someone who works for the company is a little dodgy and will cause morale problems elsewhere, but it's much harder to argue direct influence when they don't directly interact in the course of the workday.