Kind of like learning to ride a bike, except the bike is another person learning to ride a bike. It's complicated and easier for some people than others, but still a learning process that most people can get better at with time and practice.

Sometimes someone reacts negatively because they see your behavior as "non-normative", sometimes they react negatively because they're having a bad day, sometimes they react negatively because they don't know how to "act normal" either.