Could be that the girl is a sociopath but a functioning one at that. There are some that are able to live fine in human society whether through their own intelligence or proper care from family/relatives that recognized the condition early on.
Additionally a lack of emotion doesn't mean a lack of interest in other people nor a lack of morals which can be taught or instilled. So it could make sense that she would still be interested in other peoples emotions, be completely enamored by the boy mc, and want to help people in general.
omg this was adorable but her apparent lack of emotions is worrying on a psychological level. It's possible she's special even among special cases but still
I think she’s just so god damn genuine that she doesn’t need a personification of her emotions, since she basically acts completely true to her emotions.
Stay with me on this, but what if she was his emotions he tried to kill, but ended up becoming something that could help him. Like the Sixth Sense or something.
Awww!!! That was adorable! Also, I hope that she can help him with his domestic abuse. Like, reporting to the police, getting him to stand up and change the situation(if possible, I know that isn't always possible), etc.
On a side note, people without emotions are essentially like computers, they won't have free will. If this girl really didn't have any emotions she wouldn't have interfered with other people's emotion-pets(?) as she had no reason to do so. In conclusion, this girl's power is not what she thinks it is.... or it's just a plot hole.