My Protagonist Killed her Husband
Even on the rough outline, James, the protagonist's husband, is to die. That's the way to end their love story, to end it realistically, logistically.
He is painted a real villain, no doubt about it. There is no ambiguity about his character: selfish, misogynistic, heartless, etc. He serves as the background of her ruinous life, from which she would rise, like a lotus above the muddy swamp, without bitterness, without being revengeful, without losing her eternal love for James.
But the story takes its time, like life, to evolve. It takes its time, to depict the characters in all details, to reveal who they are, what they think, how they respond to each situation life brings them. Their universal truth touches the reader only after the characters mature, reflect, look backward.
By then, James has carved his space into the story's heart, becomes somewhat indispensable, although a villain. Only through his cruelty that the protagonist realizes herself, promotes herself, redeems.
So when the protagonist has no other logical choice to make the story realistic than to end her husband's life, not by killing him, but by leaving him to move on with her own life, detaching herself from the background of his villainous life, she inadvertently ends her own, killing herself, ceasing to be solely because the ending turmoils of her life has rendered her normal, typical, uninteresting.
Therefore, when the protagonist leaves her husband, ending his presence in the story, it ends. Like all love story, it ends when love dies.