My GF Disabled Son

So I'm gay and I have been dating this girl who is pan who has a disabled 16 year old. They had a car accident. She lost her leg and has a fake leg. Her son was left paralyzed from his waist down. My problem isn't him at all. It's that I feel she's crossing boundaries with both of us. He using depends and she doesn't seem to have much respect for his privacy. While I was over their house she changed him in front of me and he looked like he wanted to kill himself. We both just looked super awkward and embarrassed. She says "If we are going to be together you're gonna have to learn how to change him". At that point he's covering his face. Another time she had me come over thinking we are all gonna hang out, but she leaves me with him saying I need too learn how to take care of him. I have only been with this girl for two months. He made it very clear he doesn't want me taking care of him and stayed in his room. When she got back she was mad we hadn't bonded. I've bee trying to explain if you want us to bond you can't put us in uncomfortable situations that embarrass him. She then got mad at me for telling her how to parent. We are in a fight now. Am I wrong here. Her son's a good kid she's just putting us in weird situations.