The narrator says that Sonja believed in destiny. Ove never outright agreed with her, but he never disagreed with her either. For him, destiny was "someone" rather than "something."
This conception of destiny shows that the Ove of the present is capable of love and kindness to others, as evidenced by Sonja and the love they shared being destiny.
Ove became an orphan at the age of sixteen. After his first two weeks working on the railways, Ove sadly left the changing rooms. A man from the director's office stopped Ove and asked him if he'd be interested in staying on, and Ove agreed. Ove's coworkers thought him eccentric, but when he proved himself to be as kind as his father and just as good with engines, they accepted him. He continued his routine of eating potatoes and sausages for dinner and talked less and less as time went on. Ove had no friends and no enemy except for Tom, who, after being promoted to foreman, set out to make Ove's life miserable.
Ove's goal of being as much like his father as possible seems to be coming true: he's equally as good with engines and at this point, he's kind. This is a testament to the power of family and love: Ove's love for his father has the power to make him into the person we see here. He's also still clinging to routine, as evidenced by his dinner, and doing rather that talking, which plays into his beliefs about how a man should act.
Two years after Ove's father died, Ove and Tom were the only ones present when money disappeared out of a train carriage. Nobody believed that Ove stole the money, but when Ove was called to the director's office to testify that he saw Tom took the money, he only stared at the floor. When pressed, Ove told the director that he doesn't tell tales about other people. The director reminded Ove that if witnesses come forward accusing him, then they'll have to conclude that Ove committed the crime. Ove nodded and left the office.
Again, Ove is willing to allow others to accuse him of theft in order to be as much like his father as possible. This brings the usefulness of Ove's principles into question. Though it's certainly true that Ove's principles here bring him closer to meeting Sonja, it's also possible that had Ove accused Tom, he would've been able to avoid their later conflicts and still remain as principled as he is now.
Throughout the afternoon, two young men who worked with Tom accused Ove. The next morning, the foreman fired Ove. Tom hissed "thief" at Ove as he walked out. Ove was ashamed that he'd been fired from his father's job. In the director's office a little later, the director told Ove that Tom stole the money and then proceeded to ignore Ove. Ove told him that men are what they are because of what they do, not what they say. The director asked Ove to sign some paperwork and sent him on his way without calling the police.
The director is an honorable man. He's fully aware that Ove is simply too principled to accuse Tom, but the director is bound by the rules that dictate that Ove must be fired since he "stole" the money. The young men who work with Tom seem to embody all the qualities that Ove finds distasteful in the present. They want to curry favor and get ahead, rather than do the right thing.
Ove left the director's office. As he reached the front door, a woman from the office caught up to him and told him that the director was hiring him as a night cleaner starting the next morning. The woman passed on another message from the director: that he knows Ove didn't steal the money and he doesn't want to be responsible for firing a decent man's son for having principles. This change in job title is how Ove met Sonja as he finished his shift one morning.
We get proof now that Ove's principles brought him closer to Sonja. This begins to suggest that in the present, Ove's desire to stick to his principles will work out similarly well for him and bring him closer to the community. The director again shows that he's a decent and honorable man by hiring Ove back.