How can I help this person deal with her problems? She is my uncles girlfriend and they have kids.?

So I have an uncle who’s 4 years older then I am . He was more like a older brother to me growing up. Now he has a 5 year old daughter and 2 year old son. He’s been with his girlfriend who’s the kids mom for 8 years . They started dating after high school. I’ve gotten close to my uncles girlfriend and she’s a good person with a good job and provides for herself and her kids. She deals with my uncles addiction to drugs and that’s their main problem. She wants him to stop and he is addicted to it because he’s been doing it for a while. But she wants him to stop because they have kids and she doesn’t want a bad influence for her kids . I feel bad that I can’t help her out either way . I try to give her advice but I don’t think I can help. She also lives in a living room space which is bad . I tell her to find a place and do it for herself and her kids. But I also don’t like that they’re always fighting over the same thing. Always about the drugs and they’re old now . They should know the bad and the good. So I don’t know what’s going on with them . I wish I could help them.