Is it bad to be a friend to my uncles girlfriend?

So I have a uncle who’s 4 years older then me . He has a girlfriend and two kids with her . I have known her a few years now and I started to get to know her more now since I’ve been living around them more often. I used to live in Georgia and now I’m in New York where they live. But anyway my uncle and his girlfriend don’t have a healthy relationship since he likes to smoke and go out and do his thing. His girlfriend is always home being responsible with the kids. Btw they’re 25 year olds. But the thing is I have gotten close to her which is odd . I talk to her about my issues and she does the same with me. We’re like friends in a way . It’s odd cause I have this type of close relationship with her , she isn’t my aunt . I have aunts who actually are my aunts and don’t really talk to them like I talk to her. I feel like one day my uncle and his girlfriend will separate and have to do their own thing. I don’t want to be selfish and act like she has to be around us . I feel bad for her because she’s dealing with my uncles issues with drugs and addiction . Should I keep a distant relationship with my uncles girlfriend since one day they may separate.