She is a famous star.
He is a soldier who loves selflessly.
She was forced to marry him, and she took his kindness to her for granted. So, while she was indifferent to him, she also tried to please his brother in every possible way. Even though he was heartbroken when he found out, he still didn't abandon her. He thought she would change. It wasn't until the end, when he died, that he knew that his death was actually a conspiracy between her and his brother.
After N years, she was abandoned by his brother, and she just understood his feelings for her. Although I regret, there is no medicine for regret in the world.
When she woke up again, she swore that she would be good to him wholeheartedly in this life.