Well, remember that in this novel the relationship between Minerva and Manolo changes as the action progresses. Their relationship doesn't really start off very well as Manolo is unfaithful to Minerva early on, yet when they both become leaders in the rebel movement, it is clear that this brings them closer together. Maria Teresa gives us an insight into the strain that there marriage is under when she goes and visits them and stays in their very small house in a poor region of the country:
The drive today was horribly tense. Manolo and Minerva kept addressing all their conversation to me, though every once in a while, they'd start discussing something in low voices.
Later on, Maria Teresa hears Minerva emit a "cracking sob" and confronts her sister about what is going on with Manolo, who is out "all hours," and Minerva confesses that Manolo is having an affair.