The most clear example of sibling rivalry that occurs in this excellent novel is in the way that Dede and Minerva unknowingly compete with each other for the attentions of Virgilio Morales. This struggle is made more poignant because Dede, who is going to be married to her cousin, can't really declare her love openly, and is left to watch as Virgilio and her sister become closer and closer. Of course, this reaches a climax in Chapter 5 when Virgilio (or Lio as the characters call him) is forced to flee the country because of fear of political persecution thanks to his opposition to the Trujillo regime. Lio delivers Dede a letter for her to give to Minerva. Dede's jealousy forces her to open it, and discovers the following information:
Lio was inviting Minerva to take asylum with him! She should drive down to teh capital on the pretense of seeing the exhibit at teh Colombian embassy and refuse to leave. What a risk to ask her sister to take! Why, the embassies were surrounded these days, and all the recent refugees had been intercepted and put in prison where most of them had disappeared forever. Dede could not expose her sister to this danger.
Thus it is that Dede manages to delude herself that she is acting in her sister's best interests by burning the letter and not telling Minerva about it, even though this belief is belied by the way that she sleeps badly that night, "holding her pillow like a man in her arms." If she cannot have Lio, then she will do whatever she needs to do to ensure that Minerva will not have him either.