Melancholia means sorrow which is when a person is drowning in sadness that could lead to their lowest point. It's like an empty feeling. But when someone let the feelings out, they could dream of a new start.
So is Kanaya Mikayla as the main chracther in this story. She never feel enough of who she truly is. She is like a fragile glass that could break easily. She often gets too personal with anything someone has said to her. This condition makes her feel gloomy, sad, and comfortable being alone. Until then she realized that to live a happier life, she only needs to be confident, create her own definition of beauty, cut toxic people off, and love her own self even more by being grateful for all the things that she has.