State laws can vary on this issue, and the most reliable way for you to get an answer to this question is to call your state human rights agency to find a specific answer. Generally speaking, there needs to be a job-related reason for employers to make these kinds of rules. Usually, this comes up in the context of a supervisor supervising a subordinate employee he/she is dating. Doesn't make sense that your employer would want to restrict dating in the scenario you describe and let others do...