Who is Faith White from Keeping Faith and what is their importance?

Faith is seven and the only child of Mariah and Colin White. She is very close to her grandmother and her mother. On a particular afternoon, she and her mother visit Millie before heading out for Faith's ballet lesson. When Faith realizes that her mother hadn't intended to return home before the lesson, Faith announces that she forgot her leotard. Faith and Mariah walk in on Colin and his mistress. Faith later says that her father left immediately after the episode, and that she thought she'd done something to prompt his leaving.