Why is it so hard for people to realize when they’re interrupting others, and how can you become more aware of it?

What's the best way to deal with guests who complain about how you've set up your home during a gathering?
How did you handle being called on stage unprepared, and what did you learn from those experiences?
Does it make sense for a toxic friend to start ghosting you, but still keep a coffee cup you gave them because you see it on their Facebook page?