Edith Wharton's The Custom of the Country is a social novel regarding relationships and society. The protagonist, Undine Spragg, is a conniving young woman who has tragically mistaken the meaning of true happiness. She's looking for a wealthy husband who will buy her whatever she wants, thinking that will fulfill all her dreams. Unfortunately this gets her nowhere, and by the time she ends up re-married to her first in a series of 3 (almost 4) marriages she's got nothing to show for it except more restlessness.
Undine's story is one of tragedy. She turns into a horrible person because she makes a mistake as a young woman in confusing money with happiness. Instead of facing her character deficiencies and learning from her mistakes, Undine blames husband after husband for not being who he claimed to be. But what she really means is they weren't as rich as she'd hoped. Or more truthfully, they didn't make her happy because she can't respect herself.
Wharton's novel illustrates the importance of human relationship over material possession or social status. She does this however, by presenting a failed protagonist. Undine is not a person readers should admire or aspire to be because she's failed. She's done the opposite of what she should have with her life. In seeking happiness through finances, she's mistakenly de-valued herself and the people around her. All that dissatisfaction in her life could have been filled by devoting herself to becoming a person of integrity, but instead she spends her entire life trying to trick wealthy men into marrying her so that she can take advantage of their money.
