why did the woman I hooked up with get angry with me when I asked her to do the thing she did to me to myself?

this was recently and I don’t know if I did something wrong or not. basically we were messing around and after we were done I asked her to get me off the same way she wanted me to get her off (by going down on me) since the only time I had gotten off was when I was going down on her. I don’t know what happened after that but she start yelling at me and left so I’m wondering what happened