(Being always quite shocked by the translation Google offers for our Blog texts, I will try to give you a - hopefully - better version done by myself. Assuming that you are not that deeply interested in Berlin's city views and history, I shorten my German post a bit).
"Half she pulled him, half he surrendered..." (as I put it) is a quote from Johann Wolfgang v. Goethe's poem "The Fisherman" - maybe you like Karl Friedrich Curschmann's (18005 - 1841) version better: "half pulled by her and half sinking himself," he translated.
If you look at Ernst Herter's bronze sculpture - the title is "A Rare Catch" and it was created in 1896. it stands at a little pond bank in Viktoria Park in Berlin-Kreuzberg. . .you see that in his case it might be vice & versa. (I might even call it "Partners in Grime" :-) , because the mermaid and the fisher look both lewed).
So many German poems and short stories deal with mermaids, and all the other inhabitants of water and sea. I also love Oscar Wilde's story "The Fisherman and His Soul" - where the poor infatuated young fisherman tries to get rid of his soul to be able to live with the mermaid. And of course Frederick Leighton's beautiful picture, or Arnold Böcklin's.
There are a lot of interpretations of what the mermaid might be a symbol for - very famous is Carl Gustav Jung's "Archetype" with the devouring part of mother&woman - I would like to discuss it, but two day's ago was "International Woman's Day", and so I follow Hyacinth Bucket's (pronounce: "Bouquet") advice: "Leave it, leave it, leave it..."
The mermaid, not having a soul, is the eternal seductress; brilliantly depicted in Gottfried Keller's poem "Sea Fairy Tale" (again roughly translated by me):
(...) and kissed him the Red from his lips.
Three days she had diverted herself,
On the fourth she let the dead body
Glide out of her arms.
Then she shot up to the sunny light
And looked over to the shore;
With purple she made up her white face
And sang while drawing closer to the shore.
Not the nicest way to see women. (I might even be tempted to talk about Jung's "Shadow" now).
And not a good foundation for love... but to make a sacrifice of one's soul is also not a good option. To open up the heart: YES - let him/her in. To warm the other with one's love: YES. But don't take away the air to breathe, or the water to swim in, the elements which the other person needs to exist (but you don't, and might not even understand) - they should be accepted. How many people sacrifice their friends, their originalities, their aims when the lover just whistles once... One shouldn't: otherness is (and remains) tempting.
Otherwise it might happen that our dear prince of poets, J. W. v. Goethe, hits the nail right on the head again with another line of his poem: "and never was seen again." He speaks of the poor sinking fisherman - but we might take it as a metaphor for one partner devouring the other, wanting the sacrifice of his soul - and I know quite a lot of pairs where just that has happened.