Without having read the book, we can only guess. There could be a protagonist who is reflecting on the ten years of loving someone deeply. Maybe there's a love interest who is the object of this long - term love. There might also be a rival in love, which could add drama to the story. And friends of the protagonist who witness and sometimes influence the relationship over the decade could also be important characters.
I don't know as I haven't read the novel. But usually, there would be the person who is doing the loving and perhaps the one being loved. There might also be supporting characters like friends or family members who play a role in the relationship throughout the ten years.