This is a rather charming tale of lost love—one of the lovers having actually been lost for many years it sounds like. You weave your story in such a way that kept me guessing where it was going next. From the moment of relaxing on the couch after trick-or-treating and stealing some of her cousin's candy, to the kidnapping, to the final reveal and reunion, I never knew where I was going to be taken next. And that excitement worked really well in this piece.

I think you have a wonderful start to a story that be incredibly powerful and could take off into many different and exciting directions. Below I've listed some of my ideas on how to tighten up the story and add some things to make it more cohesive and a better experience for future readers.

One area I think you should spend some time tightening up is character motivation and reaction. When Audrey reaches into the sack for sweets and instead finds a locket with a note addressed to her, I don't feel her subsequent actions were realistic. She has a fleeting moment of confusion but she's never fearful or appears uneasy about having received a love letter from someone she's never met. As writers, we must put ourselves in the shoes of our characters and ask ourselves how would we react if we reached for candy but instead found an old-looking love letter addressed to us saying that someone was coming for us soon? I'd be a bit creeped out and concerned for my safety. This also happens when she's being escorted into her basement and into the cave—those are some pretty strong insects, I might add! We're seeing the scene through her eyes but it's mostly description of the setting. If someone's been tied up against their will by a bunch of small bugs and taken into their basement which descends into an unknown cave, I don't think they'd be noticing that the cave walls were damp or how the furniture was arranged. They'd be in fight-or-flight mode and focused on their survival and things that can aid in that: like means of undoing the binding around herself, potential weapons, and means of escape.

Another area to look at is word repetition and word choice. This is specifically about the fireflies in your story that aren't actually fireflies. They look like fireflies, but I'd advise against calling them an actual firefly to avoid confusion since fireflies do no spin silk like spiders (glow worms, on the other hand, are similar to fireflies and produce a mucus-laced silk but are a different species than fireflies). It's okay to describe the creatures as firefly-like but I'd look toward other words to use. Instead of saying the fireflies, you can use descriptive nouns such as the winged bugs, the flying insects, or the firefly-like creature. You could even label them with pejorative nouns like small demons, flying nightmares, or glowing fiends.

Near the end of your story you also make an abrupt change from third person to first person. I'm not sure if it intentional or not but it was quite jarring and took me out of the scene. The change up happens here (with both I/me and Audrey being the same person):

He rose and held a hand out to me. I took it and he helped me rise and he led me to the table where a feast had appeared. Audrey stared at the meal, knowing it hadn't been there before.

My last bit of suggestion to improve the piece would be explore more of Audrey's true self. If she's the long-lost lover of Yonah, why hasn't he tried entering our world to find her before? Is she a spirit or essence trapped in a human girl's body or is she herself and just hasn't aged? If the latter, I'd be curious how her parents or family haven't caught on that she never ages, and more importantly how she came to be their daughter/cousin. If you're going the spirit route, I think a nice touch would be to have Audrey stand up at the end and look in the mirror. In this mirror she no longer sees the young girl she was in our world, but sees the reflection of her true self. Yonah comes up behind her and clasps his locket around her neck. Together again, united in love.