Your answer is: She does not feel bound to strictly obey her culture's marriage customs.
The excerpt shown above belongs to the book "The Count of Monte Cristo" which tells the story of Dante, a man who spent 13 years unfairly imprisoned in the prison on the island.
Dante was the great love of Mercedes' life, which is presented in the excerpt above, in an argument with Ferdinand, her cousin, about marriage and love.
Ferdinand is in love with Mercedes and her family supports that they stay together, in addition, it is a cultural custom that cousins are married in their country. For this reason, Ferdinand reinforces the idea that he and Mercedes should marry. But Mercedes doesn't feel obligated to obey this cultural custom regarding marriage if she doesn't feel love for the groom and she doesn't feel love for Ferdinand, as shown in the excerpt.
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