I understand both your (OP) and the critical opinions in this thread. To be honest, my initial reaction was also half-offended, half-annoyed. You might have to prepare for reactions like these.
However, I also love to write, and completely changing one's perspective for the writing process is very brave and can be highly educating and also humbling.
You can write whatever you like. But maybe think twice about planning to publish it. Or, if you plan to publish it, stay in very close contact with different autistic people throughout your writing process who keep giving you feedback about and beta-read your book, not only ask for input about specific scenes - at least if you want to write a balanced and realistic view. Otherwise you might start with good intentions and an open mind, but end up writing a very non-authentic book, and autistic people will notice whether you've tried to really get their experiences and portray them, or whether you've wrote what you as an NT person think an autistic person might feel. If you write a book from an autistic point of view, you need to be prepared for it to be read and judged by many autistic people.
A slightly different perspective might be to use the NT love interest's first perspective as a narrator, and write about the second main autistic character through his eyes. Still researching it thoroughly to get everything as authentic as possible, but keep your NT shoes on, so to speak.
The thing is: Autists tend to experience the world, think and express themselves differently than NTs. If you write your book from the autistic character's POV, you need to adjust
everything. Not just what she says and how she acts, but everything around it too. Every scene perception, every thought process, every internal and external dialogue. If it's first person, you might also need to adjust your very writing style. Otherwise, it would read like an NT trying to imagine how an autist might feel. You
could try to do that, but it has much more potential to not be authentic, since you simply don't have those experiences. But, of course, you can seek out tons of input from autistic people and see what you end up with. It might be a massive and rewarding project. But stay very humble and open-minded through the entire process.
I hope this doesn't come off as harsh, I spoke more freely here than I normally do. But, writer to writer, I think it's important. You surely have your personal reasons for wanting to write a book like this.
P.S. I just remembered having read "The Rosie Project" and its sequels. The author, Graeme Simsion, doesn't identify as autistic and said that "he based Don [the main character] on people he has worked and socialised with rather than clinical descriptions" (
Bios – Graeme Simsion). Personally, I didn't resonate much with Don's portrayal of autism, and there are people who say it's stereotyped. But I found it interesting to read how - as I said above - the entire book was written in Don's way of thinking. It wasn't just what he said and did - it was the essence of the entire book.
