Why has Minerva been sneaking out?

In February, Maria Teresa is summoned to the principal's office to vouch for Minerva, who has been sneaking out of school. Minerva says it is to visit their sick uncle, Tio Mon, in La Vega, and Maria Teresa corroborates her lie. Later, she confronts her older sister, angry that she had to lie. Eventually, Minerva tells her that she, Elsa, Lourdes, and Sinita have been meeting secretly at Don Horacio's house, who is Elsa's grandfather. Knowing about Minerva's meetings, Maria Teresa begins to question Trujillo's benevolence.