Why does Marguerite have such a difficult time with Tommy Valdon's attentions?

One day, Maya receives a valentine from Tommy Valdon, a nice boy from the town. Maya reacts negatively, because her experience has led her to think that a male having interest in her is necessarily a bad thing. She shows the letter to her friend Louise, and Louise explains that it is a sign of affection, being asked to be a valentine; Maya tears the note up, and decides to have nothing to do with it.