What was the point?

I didn't get this movie. It's about three people who were a family but only on the surface, being nostalgic about relationships that never really happened in the first place. Is it about regret? Daddy said he had none. This seemed like the only time in their lives when they had a real chance to communicate openly with each other. Instead they kept up the illusion of normalcy which kept them apart. Maybe the point was too subtle for me. What did I miss?