Here are some story prompts, I kind of just came up with while working on my own writing. Here are some strange/bizarre story prompts that you can use if you wish.

Now it should be noted that some of these prompts are far out and crazy, so unless you have some sort of plot device that allows for the world/characters to reset at the end of the chapter, it wouldn't necessarily be conclusive to use all of these. Perhaps there is a relic that the couple come across that allow the events in this prompts to occur.

Of course, feel free to modify and adjust these prompts to best fit your story. Just have fun, like I did when I made them.

Prompts:

A – Aliens: The otp+ are doing something when suddenly aliens show up. Perhaps they are peaceful. Perhaps they abduct the otp+. Or maybe it is a full-on invasion.
B – Burglar: A burglar breaks into the otp+’s home.
C – Chocolate: One of the otp+ gives the other otp+ some chocolates. What happens next?
D – Darkness: The power goes out in the otp+’s abode and it will be hours before the power is restored. What do they do in the meantime?
E – Eggs: Something to do with eggs. Perhaps one of the otp+ cooks eggs and the other doesn’t like it. Perhaps they find some bird eggs. Maybe those aliens did something to one of the otp+ and now they have to lay some alien eggs (this doesn’t have to be NSFW, get your mind out of the gutter).
F – Frankenstein: One of the otp+ wakes up and discovers that their body isn’t their own but is actually a combination of numerous body parts from different ponies/creatures. Is the other otp+ the one responsible for this?
G – Giant: One of the otp+ becomes a giant version of themselves, walking through the city like a great kaiju.
H – Hacksaw: One of the otp+ accidentally killed somepony, now they must work together to get rid of the evidence. Or maybe both of them just do some carpentry and one of the tools they use is a hacksaw.
I – Ink: One or both of the otp+ are trying to draw/write something. Maybe something they draw/write comes to life.
J – Jack-o-lantern: It is Halloween (Nightmare Night) and both of the otp+ sit down to carve pumpkins. Perhaps once they are completed the jack-o-lanterns come to life. Or maybe one of them puts on the pumpkin and becomes possessed by a ghost.
K – Killer: There is a killer on the loss and they might be in the otp+’s house. What do they do? Do they survive… probably.
L – Lost: One of the otp+ becomes lost, maybe in the forest, maybe in the mall, perhaps in another dimension. It is up to the other otp+ to save them.
M – Monster: One of the otp+ is now a monster pony. Describe their monster pony traits and how their partner reacts.
N – Nuke: The bombs fall and your otp+ must survive in a post-apocalyptic wasteland. What happens?
O – Oxygen: The otp+ are on a spaceship (or submarine) which is running out of oxygen. Will they be rescued? What do they do in the meantime?
P – Pranks: The otp+ work together to pull some pranks on their friends/neighbors. Now do they friends/neighbors react to this.
Q – Queen: Maybe they meet a queen (Chrysalis), perhaps one of them has a fantasy that they are a queen.
R – Rock Out: The otp+ form a rock band and rock out… or maybe they just listen to some rock music instead.
S – Species Change: The species of one or both of the otp+ is changed to a different species. Perhaps an earth pony becomes a unicorn or maybe a griffin.
T – Tentacles: Tendrils for a deep sea creature, alien lifeform or eldritch horror appear in the room. Perhaps they are actually nice and have no intention of harming any of the otp+ or doing… obscene things with them (seriously why does everyone assume tentacles are always horny?).
U – Unicycle: One of the otp+ tries riding a unicycle or some other bizarre trick.
V – Vampire: One of the otp+ is turned into a vampony, how does their partner react to this.
W – Werewolf: Perhaps the roles are switched and now the other otp+ is now a werewolf.
X – Crossover: X is a hard thing to find anything for, so instead why not have the otp+ from another author (with their permission) visit your otp+ and just hang out. Perhaps they live in the same universe or perhaps inter-dimensional travel is in use.
Y – You: You the author suddenly appear in the story and the otp+ doesn’t know what to do with you.
Z – Zombies: There is a zombie outbreak and now the otp+ must try to survive. Can love blossom in the world of the undead? Will they still love each other if one or both of the otp+ become zombies? Perhaps some filly scout cookies are involved somewhere?

Well, there you have it. Some goofy prompts for you all to try out if you wish. Feel free to use them, though if you could let me know about it, that would be awesome.

Anyways, have a good day.

EDIT:

Replacements: Here are a few other ideas I had for some of the letters, that you can replace some of the letters on this list with (or use in addition to) if you want.

A - Amputation: One of the otp+ suffers an injury resulting in one of their limbs being removed. How does this affect their relationship?
B - Beach: The opt+ go to spend some time at the beach. What sort of fun activities do they get involved in while they are there?
D - Doppelganger: Someone is posing as one of the members of the otp+. Is it a changeling? Will they find out the truth?
F - Flame: The otp+ come home to discover that their home is on fire. Did somepony leave the oven on? Was it arson? What will the otp+ do?
G - Ghost: There is a ghost inside the otp+'s home. Do they exercise it or perhaps even become friends with this wondering spirit.
M - Mind Control: One of the otp+ has learned how to mind control others. Perhaps they manipulate their partner or perhaps some other characters.
P - Power: One or both of the otp+ suddenly develop superpowers. How do they use them?
R - Robot: (I honestly don't know why I didn't think of this one for my original list) it is revealed that one of the otp+ is a robot. Do they still love each other?
S - Secret Society: One of the otp+ is revealed to be part of a secret society. What dark secrets have they been hiding?
V - Virtual Reality: Both of the otp+ play a virtual reality game together.

I added a replacements section, giving you all some other options to switch out any of the ones you didn't like (or to use in addition to them).