Harriet's motives towards marriage are not altogether dissimilar from Peter's. She feels a deep sense of duty to her father, Dr. Bumstead and to her home and property. She doesn't really want to marry Dr. Alden, but it is the most sensible thing to do, given Dr. Alden's financial status through which she intends to preserve her home and watch over her father. When asked if she would still marry Dr. Alden if she chose to move to Boston where there are a host of other men to choose from, says she would because she has a duty to preserve her family's interests.