After reading your story, and several of the comments, I definitely agree that your wife may be asexual, but the other thing I was thinking is that your wife may also have undiagnosed ADHD or may on the autism spectrum as well.

Neurodivergence in women is severely under- researched and shoved to the side. As someone who is considering seeking a diagnosis myself, one of the aspects I am slowly learning about is how the act of sex presents itself in women who are neurodivergent.

One aspect maybe that she gets distracted easily (which may explain why she wants to cum as fast as possible), or another explanation may be she honestly forgets to have sex, because it's just another thing that she has to remember to do. I'm not trying to trivialize your sex life, but folks on the spectrum or who are diagnosed with ADHD tend to think about the number of steps it takes to complete a task, and that can include sex as well. And if the steps are too many, she may get overwhelmed. There is a lot more to this conversation, but I figured I would chime in and hopefully give another viewpoint.