Mattie Silver experiences an intense internal conflict in the novel. Furthermore, its resolution leads directly to the novel's tragic conclusion.
Mattie is a sweet and beautiful young woman, but she is also frail and somewhat helpless in making her way through life. Her family background has put her in the position of being dependent upon others. Zeena takes her in out of obligation. She has no love for Mattie. Ethan, in contrast, feels gentleness toward Mattie; he wants to help her and to protect her. Soon they love each other very deeply.
Despite their compelling feelings for each other, moral conventions are respected since Ethan is a married man. During the one night Ethan and Mattie share alone in Zeena's absence, they obviously long for each other and share a strong sense of intimacy, but later Ethan realizes they had not even touched.
Mattie's internal conflict is just as intense as Ethan's. She wants a life with him every bit as much as he wants to live and die with her, but she does not give in to her forbidden feelings, until Zeena sends her away. When Ethan drives Mattie to the station, she kisses Ethan, clings to him, and finally acknowledges her love. For the first time, she learns he loves her, also.
One conflict is resolved, but Mattie is suddenly trapped by another. She can't have Ethan, and now she can't live without him. She asks Ethan to take them coasting down the hill so that they never come up again. Tragedy ensues.
Mattie's internal conflict would be whether she should act on her desire and damage her relationship with Zeena or stay quite. In the beginning I don't think Mattie tried to show her feelings for Ethan even though there certainly a couple times where Ethan treated her with affection beyond that as his wife's cousin. I think what made her fully come to reality about her feelings was when they were sitting beside each other by the fire place and the tension became tangible. Mattie tries her best to stay quite but Ethan pushes her in little ways like wanting to spend the morning alone in the kitchen.