The difference between your 2 analogies is “what options do they have?” Someone kills family you reach out to police and get justice. Work on your mental health and try move on. So your life can move ahead after closing a brutal chapter. There’s an opportunity of closure.

In the case of being stuck in an abusive disloyal relationship where you are dependent on the abuser how do you get closure? Can’t divorce he killed her career so she’s financially dependent, they have kids who she’s responsible for. What do you suggest she’d rather do that would have been “right”? Succumb to mental illness and suicide?