>>My point was more related to the fact that we (myself included) tend to maintain relationships that are clearly unhealthy in hindsight.

We don't have any indication that she lacked the capacity to disengage. She was dating her boss, and may have feared retaliation.

That's one reason dating your superiors or direct reports is a big no-no. The power dynamic can only be managed by the most mature couples, and even then it's a huge liability for the company.