Subverting the soulmate trope

I never found myself very drawn to the trope of two characters meeting and just being destined for each other, where every obstacle is immediatly overcome and the world is made of sunshine and rainbows. (No hate to anyone who does like it.)

But recently I stumbled on a fic subverting this trope by turning it into a horror scenario told from an outsiders POV. After meeting the two soulmates physically merge into one person and completely lose their sense of self.

Now I'm curious; in what way have you found subversions of this trope? It doesn't have to be as horror related as my example, but anything that goes against the usual norm interests me.