What are the signs that the Johansens have not come to terms with Lise's death?

The Johansens keep Lise's trunk, which they never open, and they haven't been able to talk about her for three years.

From the text:

"See that blue trunk in the corner?" she said, pointing through the darkness. "Lots of Lise's things are in there. Even her wedding dress. Mama and Papa have never looked at those things, not since the day they packed them away." Ellen sighed.

Tonight was the first time, Annemarie realized suddenly, that Mama and Papa had spoken of Lise. The first time in three years.