Okay one more thing about lukahyuna sun-and-moon dynamics--
The Sun is thought of to give life. It protects, it allows growth, it nurtures, and it heals, it keeps us warm. It can scorch the land and cause droughts, but in general, it is kind to life.
Maybe, then, we can see Hyuna's association with the Sun as also representing her deep sense of responsibility. Her ego is built upon helping others. Her identity is "older sister" first and foremost, and that is the one constant throughout her life. She wants to be everyone's mother, not because it's good for her, but because that's where her self-worth lies as someone who raised her brother and basically doesn't have a parent. It is a heavy burden.
When the sun finally rests, the moon shows up.
Hyuna can't be a good older sister, a good ally to her friends, a beacon of justice and life.... while also loving Luka. In order to get by and uphold her moral standards for herself and her leader role with others, she needs to ignore that he was ever a part of her life.
On the flip side, when she's totally alone, when she doesn't have to think about how anyone sees her or how she wants to appear or being strong for everyone or whether or not it's morally correct, only then can she acknowledge her feelings in their entirety. She can hang a poster on her wall, tear it up, and then piece it back together as many times as she wants to, with that knowledge kept only to herself. This also, of course, applies to death-- in death, she can hold the person she still loves, and she can have the revenge that holds that love back, too. When she's alone, she can cry over her brother and still not push Luka away even when he's the one who is at fault.
Take away the responsibility or pretenses, take away the ego, and Luka immediately takes over her thoughts. Even if she momentarily gets too lost in song to think about herself, he'll show up.
Luka, a needy, emotionally stunted, codependent person who simply grew up too fast, *is* the id to her ego. In astrology, the Sun represents external appearances and motivating factors, and the Moon represents emotions, habits, and innermost desires.
