uhhhh here's uh

zombie AU where one loved one survives while the other loved one is turned into a zombie, looking for said loved one and they possibly gave each other bracelets, necklaces or etc before it even happened so they can find each other easily

and uhhhhh

alien AU where one loved one is a human(or smth like it) who's an astronaut while the other loved one is an alien, who waits patiently for their beloved astronaut to arrive back onto the ship the two share (basically the alien loved one can also yoink their human loved one onto their ship or smth like it-)

I'll add more as I brew the pot