It won't be a popular opinion but my honest answer is mainly just that I feel sorry for her. Her mum died and virtually no one cared, she was made to be a teenage bride and raped repeatedly by her best friend's dad (destroying said relationship with best and only friend), made to have his kids before she was 20, and that's just the start of it. She's making bad decisions because what else can she do? She's completely cornered, as Emma D'Arcy said. I like characters who feel they have no choice and then make sketchy decisions because of it. If she did everything right we wouldn't have a show to watch. She's no Cersei but who can be.
I also headcanon her as an extremely closeted lesbian but I know Rhaenicent shippers are loathed so I won't elaborate further
That's just a bit of extra fun for me. I'm certainly not expecting it to happen on screen or anything