A gilded frame is a symbol of wealth and a portrait is a symbol of identity. Mirium can’t find her self because she is dependent on men, financially and emotionally. Her inability to paint is an extension of this. I think this story requires an insecure and vulnerable character, but there are plenty of stories about self-absorbed, manipulative vixens. They are normally the antagonist to a wallflower but sometimes get the spotlight. It does increase the challenge of emotional connection to the reader, and there’s a gender inequality as well. Male characters can typically get away with more.