The nervousness Nina and Finn felt before the family meeting didn't stem from the things Finn had done but rather from what he hadn't done for her in the early stages of their relationship.
Nina and Finn had been together for a while. If they had been just lovers, it would have been understandable for Nina to set boundaries on how much Finn could be involved in her life.
But they had gotten engaged after just a year of dating.
Yet, despite Finn proposing and Nina saying yes, there were so many steps he had skipped. The first was asking her elders for permission—or at the very least, their blessing. The second was that even after their engagement, Finn had never properly introduced himself to the family. Even when he picked Nina up after a family dinner or gathering, he wouldn't come inside to pay his respects.
And lastly, Nina and Finn had already broken up.
Not that reconciliation was impossible, but Finn had broken Nina's heart once.