Hello (user ilovemyadhdman)!
As a male with ADHD who’s partner also has ADHD I think I can offer a slightly unique perspective on your problem.
I went 24 years without a diagnosis, and only pursued one when my partner told me about all of my co-morbids (OCD, anxiety, etc.) and that she was pretty sure I had ADHD instead of generalised anxiety disorder (my previous diagnosis).
Both of us were previously polyamorous (having multiple romantic partners simultaneously while maintaining our core relationship); for US specifically, this was more about connection and intimacy rather than any other physical aspect of a relationship. The point being: the MOST important thing (in our opinion) is just what was said by user limey: if you want him, don’t give up! Give chase instead! The most critical thing for ADHD folks and romantic partners is a combination of real chemistry, genuine honesty, dedication to having a healthy and productive relationship, but most importantly: FUN. If you both have a commitment to FUN and EACH OTHER then most of the other problems work themselves out!
To answer your direct question about whether or not the new relationship hyperfocus comes back, it’s a kind of non-answer: it depends. It all depends on MUTUAL interest and commitment, but ALSO fluidity and flexibility. The most important advice we can give you (meaning my partner and I) is NEVER lose INTEREST, and DEFINITELY keep cultivating HIS interest IN YOU (which, believe me, is still TOTALLY there, but work for us is…kind of a way of life XD).
Anyway, I hope that helps you find some peace and clarity! We both wish you the best in your pursuit of happiness 🙂