Ah, sisters. The daughter of Aureliano Segundo and Fernanda del Carpio, Meme grows up a happy and vivacious girl with fairly modern ideas about life and love. But after her boyfriend is shot on her mother's orders, she is packed off to a convent, where she doesn't speak again for the rest of her life. Her sister, Amaranta Úrsula, goes off to Belgium and returns to Macondo with a Flemish husband, whom she promptly leaves to get with her nephew, Aureliano (II).
You might think about Meme and Amaranta Úrsula as two sides of the same coin. Their personalities are so similar that their fates only seem different because of their age difference. When Meme is a teenager, Fernanda is still as powerful as ever, and so she puts an immediate stop to the evolving values of modernity with which Meme grows up.
Amaranta Úrsula, meanwhile, comes of age when Fernanda is already losing it, and after the horrible experience of her sister has once again fractured the family. Their dad, Aureliano Segundo, doesn't want to repeat the mistakes he made with Meme, so he tries to engineer a different fate for Amaranta Úrsula by sending her away from the accursed town. Why do you think she comes back? One of the overriding mysteries of the Buendía family is how drawn they are to Macondo. Why can't they just stay the heck away?