"The mermaid was stuck inside a tank. She had a tiny world in which to exist. But that wasn't only because she was in captivity, but also, because she was unique. She would not be able to breathe outside of it. She had nothing in common with those outside the tank, and what was the point of conversation other than to find points of commonality? The mermaid was on display for everyone to stare at in amazement."

Ah ok, so Marie sees herself as the mermaid, feeling trapped and on display and unable to connect with normal people both because of her gender and her class, causing her isolation. Her journey to see the mermaid is a manifestation of this loneliness as well as a need to believe in something extraordinary.

The book, immediately after: " And wasn't that somehow the role Marie played in society as well? Like Marie, because of her peculiar gifts and powers, the mermaid could not mingle with outsiders."

I feel like the writing keeps doing this. It describes a situation, the implied meaning of which is easily interpreted by the reader, and then it immediately spoonfeeds the intended message afterward, leaving no room for subtlety or nuance. Everything is spelled out in crystal clear terms, leaving me feeling like I'm not being trusted as a reader to figure things out for myself. The mermaid was not a particularly subtle metaphor either, so immediately chiming in with "and isn't this just like this character's problem??" sort of cheapens the comparison for me as it emulates patterns found in books meant for much younger readers.