I've never heard of this in English but like Jmat said it sounds really similar to 'polar opposite', so perhaps it is a play on words of some kind? As in it could refer to the souls of two people who are completely opposite to one another. Just a guess!

I searched for the movie and did find "Souler Opposite" it means what Beckie wrote, but "souler" is not a standard word. It was invented just for this movie title, to include "soul" and rhyme with "polar". It is pronounced to rhyme with "polar" or "roller."

Yes, I understand now, thank you.

I think Ed's got it. It's probably a play on the words "soul" and "polar".

I saw it in a book. And there is a movie called "The Souler Opposite".