hyphenation - What role does the hyphen serve in this context?

What role does the hyphen (it's not confused with an em dash) serve in these two contexts, and how to successfully replicate the conditions (to use it in any sentence I wish to).

You take your obligation to deliver an package very seriously - an ethic for which I am grateful.

But - you have a way of exceeding expectations, don't you?

I've searched a few sites, even this, but it's difficult when you have no firm grasp on the subject. If you realize where the quotes are from, please shh - embarrasing (also, is it correct to use a hyphen here, I have no idea).

Answer

Update : Kate Bunting has a good point. In this context, dash may be a more appropriate term. Strictly speaking, Hyphen only refers to the (-) symbol in-between parts of a hyphenated word. For example, long-distance as in They are in a long-distance relationship is a hyphen.

In this context the dash is used as a long pause, providing separation between two related clauses. It's similar in function to a semicolon and you can maybe think of it as like a double-comma.

Did you get the bread, I'm hungry. (short pause)

Did you get the bread - I'm hungry. (medium pause)
Did you get the bread; I'm hungry. (also medium pause, but perhaps a bit more archaic)
Did you get the bread. I'm hungry. (longer pause)

It's not a particularly formal manner of writing, but it's certainly not incorrect. From a linguistic perspective, so long the average speaker can understand the meaning then it's valid, even if it doesn't meet the "formal" definitions of grammar. That's not to say that the rules of grammar don't have their place, but in literature authors have always bended the rules to create the kind of feeling they desire.

For the record, I'm not sure whether (-) is technically grammatically correct or not. Maybe somebody else can weigh in on this.