The Age of Innocence is the third book in Wharton's loosely-linked cycle focused on upper class New York of the 1870's (the other two books are The House of Mirth, published in 1905, and The Custom of the Country, published in 1913). She's writing from a distance, looking backward between 30 and 50 years, but this is an era and subject that is deeply familiar to her by dint of her birth. Wharton herself was fairly unconventional - unhappily married to a man who was seriously mentally ill, she commenced an affair with a newspaperman and divorced her husband.
The Age of Innocence, unlike the other two books, is narrated by a male character, Newland Archer, who provides a bridge between the older, conventional attitudes and newer, more liberated attitudes, and is, to some degree, crushed by convention. He lives on the cusp of change, but chooses to follow the strictures of society. He is conflicted about what he really wants from his life.
On the one hand, when speaking of his future wife, he says:
He did not in the least wish the future Mrs. Newland Archer to be a simpleton. He meant her (thanks to his enlightening companionship) to develop a social tact and readiness of wit enabling her to hold her own with the most popular married women of the “younger set,” in which it was the recognised custom to attract masculine homage while playfully discouraging it. If he had probed to the bottom of his vanity (as he sometimes nearly did) he would have found there the wish that his wife should be as worldly-wise and as eager to please as the married lady whose charms had held his fancy through two mildly agitated years; without, of course, any hint of the frailty which had so nearly marred that unhappy being’s life, and had disarranged his own plans for a whole winter.
He chooses May Welland to be his wife, an athletic, beautiful and extremely proper young girl who is totally conventional. He announces this choice with desperately unfortunate timing on the very evening that he will meet May's cousin, Ellen Olenska, who, as it turns out, represents the consuming passion of his life. There are many moments during the book that are turning points, where he could choose passion, but, instead, he follows duty and societal expectation.
There is something both noble and sad about Newland Archer. He was an anachronism, even in Wharton's time - the honorable man who would sacrifice passion for domesticity. As the book continues, the shackles around Archer tighten by his own choice. At any moment, he could throw caution to the wind, leave May, leave New York, and follow his heart. But he never does, and I end up thinking more of him for the sacrifice, not less.
He could not deplore (as Thackeray’s heroes so often exasperated him by doing) that he had not a blank page to offer his bride in exchange for the unblemished one she was to give to him. He could not get away from the fact that if he had been brought up as she had they would have been no more fit to find their way about than the Babes in the Wood; nor could he, for all his anxious cogitations, see any honest reason (any, that is, unconnected with his own momentary pleasure, and the passion of masculine vanity) why his bride should not have been allowed the same freedom of experience as himself.
Archer acknowledges that May has been raised to be just that which she has become - a "blank page." She has been raised to go, innocent, from father's home to husband's home. The entire society is in a conspiracy to ensure that ladies like May never have to confront the difficulties of life. How terribly suffocating and infantilizing that must have been. But, in spite of that, she knows, of course, that her husband is passionately in love with someone else. And it isn't just sexual passion, it is also intellectual passion. With Ellen, he has found his soulmate and his intellectual equal, someone who would challenge him. May was not capable of engaging him.
Archer had reverted to all his old inherited ideas about marriage. It was less trouble to conform with the tradition and treat May exactly as all his friends treated their wives than to try to put into practice the theories with which his untrammelled bachelorhood had dallied. There was no use in trying to emancipate a wife who had not the dimmest notion that she was not free; and he had long since discovered that May’s only use of the liberty she supposed herself to possess would be to lay it on the altar of her wifely adoration.
In the end, what does Archer gain? Well, his children of course, who love him quite dearly. And May, who, limited as she was, sacrificed as well.
He had been what was called a faithful husband; and when May had suddenly died — carried off by the infectious pneumonia through which she had nursed their youngest child — he had honestly mourned her. Their long years together had shown him that it did not so much matter if marriage was a dull duty, as long as it kept the dignity of a duty: lapsing from that, it became a mere battle of ugly appetites. Looking about him, he honoured his own past, and mourned for it. After all, there was good in the old ways.
By the end of the book, Archer's world has changed inalterably. His son is marrying the daughter of Julius Beaufort, a young woman who resembles Ellen Olenska in many ways - sparkling, vibrant, unconventional - with the approval of society. Archer knows that it has changed too late for him - he is the old guard, his children are the new. They will get their chances. He sacrificed his for duty.
Wharton knows how to end her books with a knife twist to the gut, and we get one here, too. Archer doesn't hold out for happiness at the end. He lived the life he chose, and he will honor that choice, painful, limiting, sometimes sad and always dutiful, even to the end.
He sat for a long time on the bench in the thickening dusk, his eyes never turning from the balcony. At length a light shone through the windows, and a moment later a man-servant came out on the balcony, drew up the awnings, and closed the shutters. At that, as if it had been the signal he waited for, Newland Archer got up slowly and walked back alone to his hotel.