Controlling partner?

What does a person do when they care about someone in an unhappy marriage? This person’s partner is very controlling and expects them to be a live in maid and servant. Now this person’s partner is even being more controlling and not letting them visit their family in a different state? How does one help someone like this? There’s a HUGGGGGE stigma of divorce in our culture. I just wish this person would stop giving away their power to their partner. Sometimes I wonder what’s the truth because I keep hearing rumors not directly from the person. I am worried though because from what I’ve personally seen their partner treats them like a servant. They never help out and expect them to do every household chore and raise their child. No help at all. Literally, not helping at all. Expect perfect meals.

Now when it’s time for everyone to meet, their partner isn’t letting them go. This is what I’ve heard, no confirmation from the person as they are private. I just want to help them. I feel like if this is true, then they are just giving away their power more and more and how long can this go on for? I don’t know if I make sense because I don’t want to go onto specifics in case this person also uses this app.