In the following citation, the reader can see Mrs. Dalloway's thoughts about Peter and why she didn't marry him. She also has many insights into the nature of the married life. She realizes what kind of relationship she can tolerate and what she cannot. She and Peter fought and he wanted so much closeness and required a lot from her. She chose not to marry him.
For they might be parted for hundreds of years, she and Peter; she never wrote a letter and his were dry sticks; but suddenly it would come over her, If he were with me now what would he say?—some days, some sights bringing him back to her calmly, without the old bitterness; which perhaps was the reward of having cared for people; they came back in the middle of St. James’s Park on a fine morning—indeed they did. But Peter—however beautiful the day might be, and the trees and the grass, and the little girl in pink— Peter never saw a thing of all that. He would put on his spectacles, if she told him to; he would look. It was the state of the world that interested him; Wagner, Pope’s poetry, people’s characters eternally, and the defects of her own soul. How he scolded her! How they argued! She would marry a Prime Minister and stand at the top of a staircase; the perfect hostess he called her (she had cried over it in her bedroom), she had the makings of the perfect hostess, he said.
So she would still find herself arguing in St. James’s Park, still making out that she had been right—and she had too—not to marry him. For in marriage a little licence, a little independence there must be between people living together day in day out in the same house; which Richard gave her, and she him. (Where was he this morning for instance? Some committee, she never asked what.) But with Peter everything had to be shared; everything gone into. And it was intolerable, and when it came to that scene in the little garden by the fountain, she had to break with him or they would have been destroyed, both of them ruined, she was convinced; though she had borne about with her for years like an arrow sticking in her heart the grief, the anguish; and then the horror of the moment when some one told her at a concert that he had married a woman met on the boat going to India! Never should she forget all that! Cold, heartless, a prude, he called her. Never could she understand how he cared. But those Indian women did presumably— silly, pretty, flimsy nincompoops. And she wasted her pity. For he was quite happy, he assured her—perfectly happy, though he had never done a thing that they talked of; his whole life had been a failure. It made her angry still.
However she still loves Peter and that she cannot deny. She misses him, even though she doesnt say it outright. She is also angry at him that he never made a good life for himself.
Mrs. Dalloway is the kind of novel that shows her inward thinking. In almost every passage you can learn something about her.
This citation is from the first page or two.