I think all the couples are meant to be showing their own marital flaws, while trying to show Bobby the joys of marraige.
I think Harry and Sarah are the most real in terms of what long-lasting relationships look like, but Paul and Amy are the reality of most relationships.
Speaking of Paul and Amy, i'm currently playing Paul and actually have a problem with how neatly their almost breakup is fixed.
"Y'all have a GRAND day now"