Humans are complex creatures, and relationships between them get pretty complex as well. Some things you should accept, others - do something about. For one couple, fighting and breaking up every evening to make up every next morning is fine, while the othersuffers from it without speaking up. One thing about the job is just how the way things are, while another unhealthy yet stuck due to neglect or a certain level of apathy.
Where's this line? I get the feeling that, despite the vastly different subjects, it's stays the same or similar: this is fine, but this next step is towards hell, so you better turn around.
You draw that line thoughtfully for yourself.
You can't "stage an intervention" without careful consideration. Will your intervention make things better or worse?
Some people will run into a burning building. It's hard to know until the situation arises.
But when you do stand up against a perceived injustice, it's an identity-defining moment. This reminds me of one of my favourite old #askhubski posts, "What is Your Lame Claim to Fame." It yielded this answer:
It's a fine balance between two things: "How much will my inaction affect me" (and that includes psychological effects like guilt) VS "How much effect can action have on me " (which is, most often, physical and professional). At least for me. If I couldn't bear to see something unfurl, I do something about it. If helping would cost me more than I would be fine with parting for that situation, I don't act.
So really - I know it's going to be a hard line to draw for you, with your previous posts - but you have to act for your own best interests.