Main characters never die?!

She was just a simple high school girl who enjoyed her boring, everyday life. Until the day she fell into the ocean in a boating accident and lost consciousness. She woke up in the body of a baby and as an avid romance novel reader she knew exactly what had happened. She was reborn and entered a book. Fortunately, the names were familiar to her, so she knew which novel it was. The only problem was that the novel ended with the main character's marriage and she was their child. So this was after the end of the novel and she had no idea what was going to happen ...