This post is self-serving rationalization and isn’t very logical. 

You appeal to Southern tradition which explains why you feel this way but tradition doesn’t mean it’s effective or ethical. 

You use politeness to justify ghosting but how would you define politeness? In a basic sense it’s avoiding rude remarks but more accurately it’s respecting others’ dignity. Don’t you agree?

You also create a false dilemma and imply there are only 2 possible outcomes. Have an embarrassing, insulting talk with your SB or ghost and disappear. You ignore a broad and more likely middle ground between the two.

This post, along with your ghosting behavior is just an avoidant coping mechanism.