The sea that once was her home is about to swallow the Little Mermaid, who is turning into foam. This is the consequence of the Prince loving someone else more then her. She could have saved herself by stabbing a dagger in his heart on the night of his marriage. But she loved him more than her own life and threw herself into the sea. Knowing that she would ultimately dissolve into it…
“She would rather turn to foam than kill him” is after “Ophelia” by John Everett Millais.