What are the benefits of maintaining strong boundaries in relationships, especially with challenging personalities like narcissists?

Is it cool to look at a picture and sing to it and believe it will become alive?
Why do some people get surprised when they're turned down after a date where they were clearly trying to be cheap? What's going through their minds?
How do you strike a balance between being hospitable and setting boundaries when friends or acquaintances want to visit Orlando?
Can a family relationship ever be repaired once someone has fundamentally disrespected your identity?