I could see this phrase being used during a divorce if the other partner realizes it was their fault.
I, too wondered about when this would come up in conversation. Some of the phrases may seem oddball, so think of them as something you might see on television.
But remember that their goal is to teach a language, not have people memorize phrases. As an efucator myself, i sometimes throw oddball questions at my students to help them oush their boundaries.
At a divorce, at a funeral, ... my first thought was when these two people meet 10 years after their separation - then it's a completely natural thing to say.
I'm often surprised at how often people claim "this sentence can't be used in real life" only because they somehow fail to imagine an appropriate situation.
That aside, yes, the main goal is to teach the language - morphology, syntax, vocabulary - and these sample sentences aim to do just that, in a planned and structured manner. The practical applicability of the specific sentences is secondary.