Why does Lily not touch Mary's heart?

After the story, the Daughters begin dancing, and then each of them slowly walks up to the statue of Mary to touch her heart. Lily is compelled to do the same, so she rises and walks toward Mary to touch her heart. As she does so, June stops playing the cello, and Lily realizes that she is not included in the ritual. August scolds June for her inhospitality, and Lily faints.