Main reason: Cong**ital Heart Disease

MC’s mother is a genius famous painter who died with the same disease so it’s a genetic disease. Her parents had a misunderstanding that I think resulted into her mother’s death, and she died alone in a hotel with her series of gloomy paintings waiting for her husband to realized his wrongs and also to take her away.

Yet it didn’t happen. So the father married his first sweetheart after his wife’s death, I dunno exactly when tho, which made MC dislike/angered towards his father.

MC also has an adopted brother (former cousin) who have the same disease. She actually watched how her brother fell in love and die from his disease. This brother actually left his former sweetheart to not burden her. So in the end, this sweetheart married someone else and is happy with her husband. So MC watched how his brother being heartbroken and happy for his love, also how he fight for his life during his series of operations, but died anyway.

But before that, ML doesn’t know MC’s family so he misunderstood that MC is having an affair with MC’s brother. So.. MC used this reason to broke up with him. Also, she doesn’t want him to know that she has a disease as to not have him suffer with her.

Also... because MC’s brother actually requested MC to accompany him for four years in this battle for life.

Sooo it’s a mess, everyone has their own selfish and selfless reason. But in the end, she decided to live her remaining life loving the ML.

But! It’s a happy ending ‘coz she had a successful operation and able to live once again with ML.

But! There’s a book 2, which I only read a few parts and it’s also angsty but happy ending. It tells the detailed story of their school days and married days (MC wants a child but because of her poor health the ML doesn’t want her to)