I am often asked for recommendations regarding books or other resources for neurodiverse couples. There is at the moment an increasing amount of solid information available, due to increased attention to neurodiversity in general, as well as to how neurodiversity relates to couples in particular. This is good news.
My suggestion is to remember that whatever you read, use your own powers of discernment to decide whether what you are reading is helpful to you, and whether the material is applicable to your own partner and your relationship. No two autistic individuals have all the traits of autism, nor do they express the traits they do have in the same way as others do.
At the level of biology, autism is autism. But autism is not all there is to a person, as you know. Everyone has a unique combination of personality, temperament, family history, education, intelligence, preferences, talents, interests, whether autistic or not. If you've met one autistic person, you've met one autistic person. Your partner may be autistic and not demonstrate all the behaviors you are reading about in any particular book or article, including articles of my own.
There are vast differences between autistic men and autistic women. Most of what you find will be based in research done on men, though this is changing. Be mindful of this.
When you come upon a term such as Cassandra Syndrome, be careful not to over-identify with it. Let it inform your thinking without seeing it as a definite role you play. The reality of your personal experience is more complex.
When you watch Rain Man and other films showing autism, be careful not to generalize. Even shows like The Big Bang and Atypical only represent certain aspects of autism, and oftentimes do so more as caricature than characterization.
You will find many online quizzes related to whether someone is autisic. Be careful. Only one is really significantly developed and researched, and that is the 50-question instrument developed by Simon Baron-Cohen, PhD (you can find this on his website linked below). Even this was developed as a means of suggesting whether a formal evaluation for autism might be warranted. It is not itself diagnostic. In other words, please don't use these quizzes as definite gauges for whether someone is autistic. They're simply not valid unto themselves. They are merely suggestive, and imperfectly suggestive at that, since many autistic individuals score below the threshhold for recommending an evaluation.
With regard to specific authorities whom I hold in the highest regard, two individuals come to mind.
Simon Baron-Cohen, PhD, is the Director of the Autism Research Centre at the University of Cambridge. He has many active researchers working with him, and any time you see his name, the work is worth exploring. Caveat: Professor Baron-Cohen has revised his thinking regarding his formerly held position of visualizing autism as extreme male brain. If you come across this term in your reading, dismiss it as old news. The Autism Research Centre has many resources worth exploring. And yes, Simon Baron-Cohen is related to Sacha Baron-Cohen. They are cousins, and both are brilliant.
Tony Atwood, PhD, is an Australian psychologist whose lifelong clinical work with autism is peerless. If you see his name, you can trust that what you are reading comes from a sound clinical perspective from an intelligent and compassionate mind. He has written and coauthored many books, the primary among them is his first, entitled The Complete Guide to Asperger's Syndrome. Even though in the USA, Asperger's Syndrome is no longer a diagnostic term, the book itself (written in 1997) remains a go-to guidebook for beginning your exploration of autism. http://www.tonyattwood.com.au/
Even some of my own articles, which are linked on a separate page, contain language that is no longer in clinical use in the United States, such as the term Asperger's Syndrome. The information remains valid, but be mindful that language changes.
Remember that you are the expert on you. This means that you are free to accept and disregard anything you read on the basis of whether it is truly applicable for you. However, continue to read and do your research. You may surprise yourself and come upon something that resonates deeply weeks after you read it, when at the time it seemed irrelevant to you.
I send warm wishes to you and encourage you to remember that you loved your partner enough to join your lives. That love may feel a bit tarnished after years of neglect. If it is truly cold ashes, then you have some hard choices to make. However, and more likely, if there are still embers that glow even faintly, you can bring hope to your relationship with your new understanding of neurodiversity.
With Tony Atwood in London