A: “Is there a term for that thing where you like someone a lot and it fills you with this feeling of fizzy energy and potential, like you can feel every electron in your body zipping around?”
B: “That's a crush.”
A: “Okay, but what about when you play out daydreams in your head of what it would be like to date? And it's so sweet it's like your heart has toothache.”
B: “Yes, that's Future Abstract Plural.”
A: “Wait, there's more. You play out the daydream, but because of who you are as a person, you always gravitate to how the relationship ends. Like, not catastrophically so, just the mundane separation of tectonic plates shifting over years? That leaves you shaking with quiet but gentle grief?”
B: “Uh-”
A: “And then whenever you see them, the crush is kinda gone? Because you already processed the end of that relationship a dozen times and have arrived at a place of wistful acceptance? So when see their face and you're sad, but kinda hope for their happiness, but also definitely don't wanna smoosh their face anymore.”
B: “...”
A: “...”
B: “Okay, there's two things that could be happening here. Number one: your future self is continually sending the memories of this relationship back in time. Probably via a sympathetic distraction broadcast. But every time, you fail to heed the warning and have the relationship a little differently. So they keep sending the warning, commandeering your idle fantasies for their memory dump missives. Eventually, they grind your feelings down until the shine wears off.
A: “And option two?”
B: “It's a trauma response.”
A: “Okaaaay.”
B: “Either way, it's called Eternal Sunshining.”
