There is no law or really good principle that suggests that shareholder profits matter above aspects such as ethics; that is just a misrepresentation of something a famous economist said.

It matters for the very obvious reason that a less senior employee may feel pressured or may lose their job when the relationship ends, that usually office affairs result in other employees feeling compelled to keep secrets, that it may result in others losing out on promotions to the employee in the affair, that they often result in abuse of resources, because it opens everyone up to blackmail, that it’s a display of bad judgement and ethics, etc. etc.

It’s nothing at all to do with political correctness.