Are there people who truly don't want to be loved?

I'm really struggling right now with this. I fell hard for my oldest friend in the world. Her and I will be friends for life. But I also want to date her. She didn't know what she actually wanted when I finally asked her out. But she has finally decided that she doesn't want to be in a relationship with anyone. Of course I respect that and I have always loved her because of how independent she is. But it also makes me sad that she doesn't want to be with anyone. Her and I will always be the best of friends. And I'm struggling to accept that she doesn't want love in her life. How are people truly happy being alone? I need some help understanding this.