When Ove first saw Sonja, he'd just finished his cleaning shift and was supposed to take the train home in the opposite direction. When he saw her on the platform, however, he got back on the train, convinced a conductor to lend him spare clothes, and sat by her. She greeted him warmly and showed him the books in her lap. Even though Ove said he didn't like reading much, she proceeded to tell him about each book. Ove thought he wanted to hear her talk about things she loved for the rest of his life. Years later she told him that she was confused when he sat down with her, but he was kind, listened, and she liked making him laugh.
Ove's decision to do something uncharacteristically spontaneous speaks to the power that Sonja held (and still holds) in his life. Even at this early stage when the two don't know each other, Sonja enjoys making Ove laugh and come outside of his shell. This shows that she's going to be a force in his life that encourages him to step outside of his rigid principles, do spontaneous things, and take himself less seriously sometimes.
Sonja was studying to be a teacher and made an hour and a half journey each way to school. Ove made the journey with her that day, which was in the wrong direction for him. When they got off the train and she asked where he was headed, he said something vague about doing his military service. She said she was going home at five and boarded her bus. Ove walked around the town and found a tailor's shop that agreed to press his shirt and pants, then slept in the train station. At four he went back to the tailor's, met Sonja at the train station, and rode the train home with her. He did that for three months. Finally, she got tired of Ove not asking her to dinner, so she invited herself.
It's important to note that teaching is a profession that by its very nature includes giving back to the community and helping others. This shows that Sonja is very concerned with being a part of a community and serving it, which explains some of the actions that Ove described earlier, like providing Jimmy lunch weekly. Ove shows that he's very loyal already to Sonja by riding the train with her. This sets up the knowledge that Ove is willing to step outside of his principles for her, and only her.
On Saturday, Ove put on his father's suit. This attracted the attention of his landlady. As Ove was at the door she called after him that he should get his date flowers. He waited for Sonja at the train station for more than 15 minutes. He felt anxious that she'd never come, but he stayed anyway. The narrator tells the reader that Ove didn't know it, but he was destined to spend so many 15-minute increments waiting for Sonja, Ove's father would have gone cross eyed. Finally Sonja arrived and was thrilled to receive the pink flowers.
This experience of waiting for Sonja provides Ove an experience in which he is rewarded for violating his principles of timeliness. This lesson apparently sticks, if he goes on to put up with her lateness for the next 40 years. This experience also shows him that some people, Sonja in particular, can be trusted. She doesn't stand him up and she follows through with her promises, even if she's late.
Ove had eaten before the date so that Sonja could order whatever she wanted and he would still be able to pay the bill. He felt that the waiter knew that Sonja was too good for him. He listened to her tell him about books and films and her studies and finally told her that he'd lied about doing his military service. He apologized for lying to her and Sonja just smiled and asked Ove to sit back down. She wasn't angry and had already figured out he wasn't in the military.
Again, Ove's decision to not follow his rigid principles of honor and truthfulness doesn't have a bad result here. Sonja already knew he was lying and further, she doesn't care. These experiences plant the idea for Ove that occasionally breaking or bending one’s principles doesn’t always have disastrous consequences. Indeed, sometimes the consequences are truly positive.
Sonja asked Ove what he wanted to do with his life, and he answered that he wanted to build houses. She angrily asked him why he wasn't doing that. On Monday, she showed up at Ove's house with brochures for a certification course for an engineering qualification. They decided that they were an item, and Ove enrolled in the course.
Despite Sonja's habit of encouraging Ove to not follow his principles so strictly, here she encourages him to follow them—in terms of the big picture, rather than just the details he usually gets caught up in—when she insists that he actually do what he wants to do, not just talk about doing it.
Ove got a job at a housing office and worked there for more than 30 years. He and Sonja married and agreed to have children, so they moved into the row house near the forest. And now, less than 40 years after their first date, the forest that once surrounded the row house is gone. Six months ago, she comforted Ove as she lay in the hospital, and then died. Ove buried Sonja on Sunday and went to work the next day. The narrator says that if anyone asked, Ove would say he didn't live before he met Sonja or after her death.
Time has passed and things have changed, and for Ove, that change hasn't been for the better. These flashbacks show that Ove had exceptionally happy times in the past, and the changes that are taking place in the present and the very recent past are in direct opposition to those memories, making him feel all the worse.