If I had to admit it, I would say yes, creating a plot for a story is very difficult. Because almost every plot has already been thought of, so it's hard to create something and fully make it your own without it being similar to something that already exists.

Throughout my years on wattpad, I've followed a simple solution for this, and that is:

character(s) + situation x obstacles = ending.

This formula can also include a goal, but it's not entirely necessary.

First you must choose your characters, then place them in a particular situation ( what is the situation? ). Then they must overcome the obstacles to create an ending. Which could be an expected ending, a happy ( for now ) ending, which technically means cliffhanger ending, or an overall happy or sad ending.

EXAMPLE: Obsession

-INCLUDES SPOILERS-

For the character(s) it's Sanghee and Jimin.

For situation, it's that Sanghee has had an obsession on Jimin, her neighbor, since they were kids.

For obstacles, it's that Jimin has a hard time showing feelings and "loving" people, so that creates a bit of conflict for their relationship.

And for the ending, it's going to be a happy ending, because although they had a lot of differences, Jimin learned to change for the better.

_____

In reality, creating a plot would take me a few months if I want it to be unique, and if I want to put my own little twist to it.

After this step, you should be able to fill in the gaps, which includes dialogues, other characters, filler chapters, character actions.. etc..

This formula is my key for creating a plot. But also understand that it might not work for everyone. It takes a very long time to create a unique plot. So when doing this step, make sure to take your time and put lots of effort into it!