She fell in love with a man who already had a family and had his child. Regardless of the cost of being expelled from the family, she insisted on giving birth to the child. She originally had a bright future as a pianist, but at that time she was just such a stupid innocent girl, willing to abandon the whole world in order to pursue fruitless love.
To her, that man was the first person in her ignorant world.
But since the birth of that child, she realized that that child was her world.
You must grow up well, Hayato.