Disclaimer: I do not own any of the characters mentioned in the story. They are the respectful property of Paramount; I just write stories about them.
After Voyager's return to the Alpha Quadrant, Tom became a holo-novelist to support his new family. At first, everything was perfect, but when his publisher kept pushing him for a new novel, he started feeling the pressure of his new career. He became frustrated with everything to the point where he would lock himself in the den for hours at a time. As a result, B'Elanna was also becoming frustrated with her husband.
She as well as working as the liaison between the federation and the Klingon Empire, she had also become more of a housewife. Usually she had Tom to help her with Miral and the household chores, but now that he was in the den most of the day, she was left to pick up the slack.
This lead to more fights between them, and after one of their bigger fights, they decided that it would be best if they gave each other their space. So Tom moved in with Harry, who lived in the apartment complex across the street, and since Harry was on deep space missions ninety percent of the time, Tom had the apartment to himself when Harry was gone.
They were both hesitant to tell their parent's about what happened, but they knew they had to sooner rather than later. Tom told his parent's, and B'Elanna told her mother. Tom's parents took the news with grace. However, B'Elanna's mother didn't take it so well. She went on about how B'Elanna should just divorce Tom, even after B'Elanna told her that she still loved him. Although she doubted that he stilled loved her.