He was the person who took her out of her small bubble, who showed him the world, who made her feel to be loved, trusted, and protected, to want something from life, to dream, and still be happy in whatever you do. How could she not fall in love who taught her big things in the simplest way?
She was done with defying the idea but she didn't regret it. So what if she couldn't be with him in the end, she had enough to learn and cherish from David. She wouldn't forget him but this will lead her to a life where she'll view everything from a broader perspective, she wouldn't be confined, discouraged, and lack confidence anymore but trust people and make friends. She has to understand the positive side of this relationship they shared and benefit from it. They were par the immature stage.