At first, Kit's relationship with William is an opportunity to escape the dull routine of her uncle's house. She is not attracted to William and has little in common with him, but she is flattered by his interest and eager for diversion. As the relationship continues, Kit knows that she does not love William, but she believes that marriage to him will provide her an escape from her dull life. Although Hannah tells her that without love, there is not escape, Kit still toys with the idea of accepting William when and if he asks.
After the theft of the charter, Kit comes to realize that she respects William; however, she still does not love him. The real truth of their relationship comes to her after the trial. William's advice to her is not to associate with people like Hannah in the future. He can not understand that Kit was honoring her own integrity by refusing to turn away from a friend, and from a good woman, just because it violates society's rules. Kit is certain that they two will never have enough in common to be happy together, and so ends the relationship.
Kit realizes that she doesn't love William - she just wanted to marry him to escape from the life that she was in. More importantly than that though, Kit knows that her cousin (Judith) is in love with William and she doesn't want to hurt her cousin.