My personal opinion is that if someone is taking extensive notes on me, much more extensive than any other individual in their life, out of romantic interest, then I would, as a gut reaction, get creeped out. I might change my mind given further explanation though.
Regardless of whether I cut off relationships, just how worried I would be depends on many factor. Gender is a factor (I would be scared of obsessive men for different reasons than obsessive women, e.g. legal biases for either case), but there are many other red flags too, such as if said person is a coworker or senior, if they have a history of abusive, violent or obsessive tendencies, and if they are beloved by others who might come to their defense to attack me.
A key difference between this situation and a therapist taking notes on a patient is that the patient signs a consent form to the process of therapy, which is explicitly explained to them. They have rights as a patient and have official avenues of complaint if the therapist abuses their power. I would argue, that in a business setting, it is also implicitly agreed upon that the parties parties involved are keeping track of information relevant to business, but not that would be inappropriate for a business setting.
The creepiness factor is that the other person, in personal relationships, rarely explicitly consent to having detailed notes about their personality and history recorded, nor may reasonably expect that to be the case. Now, there are many people in my life whom I trust, and I would certainly be okay with them taking notes about me. Especially given the explanation that it is something that helps you navigate relationships, and the possible neurodivergence context. However, the main issue here, putting myself into the shoes of this Angela, is that I never got the chance to consent, neither explicitly nor implicitly.
I know I don’t have a right to not be recorded per se, but it would certainly be nice to be asked first, and otherwise not have people write detailed notes about my personal history as if they’re my biographer.
Thus, having thought about this topic on and off, I suppose it may be most ethical to close friends whom you takes extensive notes on, explain that you do this thing and why you do it. If they know that you struggle with relationships otherwise, as you have explained to us, then I presume most would find it to be a quirk of yours but not mind too much.