Something I've wondered for a while.
Plenty of introverts understand that extroverts genuinely enjoy lots of social interaction and things that we find heinous, like surprise visits or smalltalk bring them joy. We may not understand why however we're aware that it does.
Extroverts on the other hand can't seem to fathom that some people don't want to socialise and enjoy being alone. You see this with people getting offended that their relatives don't want them to pop in unannounced, upset that their friend declined an invitation, or insisting on building people's confidence when the person isn't shy they're just quiet.
What's the reasoning for this? It always irritates me somewhat.