That's the part I don't get. "Don't date coworkers" is a heuristic/warning for self-guidance, not a dogmatic rule for management to impose. Aside from the typical "chain of command," rule it's none of my business. This heuristic is to help people avoid any actual or apparent nepotism while in a relationship and petty jabs afterwards, both of which Horvath ironically faced from people who didn't respect her relationship.