You do not have to have a mechanical description of your deck. You just need to explain why it fits into the theme. And if you think you need an elaborate story for people to understand, then you are either underestimating your own abilities or the minds of everyone else. Almost everyone else here has perfectly good explanations of their deck.
Let's see about that:
Serket: "story later" <-- thenewguy thinks he needs a story.
Collapse: "this may or may not be a placeholder"
Sorrow's Blade: "Story to come soon" <-- ddevans96 thinks he needs a story.
Arachnophilia: Has a story and a mechanical description. Without the story, there's no connection to the idea of romance in the deck at all.
Ophelia: Fits your description, but relies on common knowledge of a story we've theoretically all read.
Crazy Eights: Fits your description.
Darkangel: Fits your description, but offers storylike elements as part of explaining the theme.
Kebechet: Has a story but doesn't explain why the cards fit the theme at all.
Agony: Fits your description.
Lotus: Relies on a story without any other explanation of why the cards fit the theme.
AI10v.3: Relies on a story without any other explanation of why the cards fit the theme.
Xinef-Ra: Relies on a story without any other explanation of why the cards fit the theme.
Love Potion: Fits your description, but offers storylike elements as part of explaining the theme.
Nightingale: Fits your description.
Torch: Fits your description, but offers storylike elements as part of explaining the theme.
Spirit of Steam: "story to come"
Yearning: Fits your description, but offers strong storylike elements as part of explaining the theme.
Vengeance: Fits your description, but offers storylike elements as part of explaining the theme.
PlanetStar: Fits your description, but offers storylike elements as part of explaining the theme.
(I ran out of time here, I think I've made my point.)
So, if this isn't a storytelling competition, why are everyone's "perfectly good" descriptions of their deck almost all either partially or entirely story-based?
More importantly, you've avoided the key question: how can you connect a purely mechanical set of in-game items to a purely aesthetic concept without creating some form of story to explain the connection? And, at that point, how is this not in some profound respect a measure of your ability to tell that story?