In all the time I’ve been on this forum, there have been many people with this same challenge. They’ve all said they wished there was a course that could teach this. I wish there was, too. This stuff is really hard to teach!
I learned to read subtle social cues throughout my whole life. Plus, I was raised by a parent who has a style of making me read between the lines to “mind read” what she wants from me. So, I think I am really good at this skill. And still, I am often left baffled about people’s behavior, just like you.