'K, this is gonna be tricky. I've been planning this short for a while, but I still don't have a feel for how it should start, or what, exactly, should happen. In fact, I'm still kinda looking for a source of conflict. Blaaargh, maybe this isn't a good time to write this? Of course, that's a classic procrastinator's excuse...
I'll lay out a basic framework to build upon.
So, at some point, maybe at the start, this girl is meeting her best friend and/or her fiancee at a cafe, and the two-three of them banter. It's mentioned that in this world, marriage is performed by psychically linking the minds and thoughts of two individuals together, and the girl is having second thoughts about the process, though she's vocalizing them in a joking manner.
"Haven't any of you heard rumours, though?"
"You know, that there are these crazy rogue psipriests who take control of your mind when they do the ritual and turn into crazy zombie slave things!"
"Aw, c'mon, [insert name]-"
"No, it's true! I heard about it from... uh..."
[Insert name] sighed. "Touche."
Okay, sucky dialogue and poor humour. Work on it.
Later, when she's alone or her fiancee is the only one there, she vocalizes her fears or has an internal monologue. It turns out the real problem isn't with the binding ritual itself, it's with the surrender of her freedom and her secrets. She begins to consider whether it's worth going through. At some point, either here or during the ritual, she decides her love for her spouse is greater than whatever fear she may have and chooses to go through with it.
At the end of the story, they finally go through the titular binding. Happily ever after, yadda yadda yadda.
It's simple, that's good. It's also very different thematically from anything else I've ever done, which is good, I suppose. A good author must constantly stretch their comfort zone.
There's a lot to think about, definitely, and I hope that by doing so, I'll be able to turn this into a great story.