To understand this show, you must understand the cultural symbolism of a sirens.
I looked up the definition before watching, and glad I did, because I thought sirens were mermaids, but I did know of their abilities to use singing as symbols of temptation and danger.
I did not know their symbolism of representation of the "allure of the unknown and the risks associated with succumbing to desires that can lead to destruction".
If you understand this symbolism, you'll understand the underlining meaning to this story.
All of these women are sirens. Gathering men using their song, but in the end you find out the men are really the evil symbols of danger and two of the sirens break away from the toxicity of the men in their lives.