In my experience, the harder it is to dissolve a relationship, the worse it is. There's no incentive for good behavior because the other person has to stick with you no matter what. Adult relationships with siblings and parents are often quite toxic for this reason.
Adult relationships with parents and siblings can indeed be toxic.
However, you aren't actually forced to stick with them no matter what.
In fact, for the most part, it takes consistent effort to keep family in your life.
As a contrast it's much harder for most of the population to quit their job and stop associating with their boss and yet the employer-employee relationship is often a lot less toxic.
There's usually _much_ less emotion involved in the employer-employee relationship. In my experience when a significant amount of emotion gets involved, it's more often negative emotion, and then you start hitting problems where you feel trapped in a job with no alternatives.
Many of the worst spousal relationships are ones where one spouse feels trapped and cannot leave for religious, financial, social, etc. reasons.