Mailice here with a short review!
That was a very philosophical story you wrote here. A little different than expected, but that makes it unique in a certain way. The tone here is from a particular point of view; calm. There is this relaxedness and timelessness that you have written here. As a reader, you don't know where or who the characters are, which helps the story to be read no matter where or when.
You are addressing a question here that many have had before you, but you show that it doesn't always have to go by a cliché to have an effect on the reader. From the little you get to know of the characters and how they speak, you learn some details that can assume that it is hard to explain what love is for at least the responder. I liked the self-reflection in places as it continued to exude that calmness that you could see everywhere else. I don't think it detracted from the text in any way.
I think with short stories like this, it's always quite hard to find something that could really be changed or not, because the message you want to express here falls into a different direction, like most short stories.
Other points I noticed while reading:
“Have you ever fallen in love?” The question startled me from my reverie.
“Have you ever fallen in love?” His eyes remained fixed on the sunset, always staring straight ahead.
That alone is a good start to the short story. I like this repetition and how the second "Have you ever fallen in love?" is pronounced in a much softer tone by itself as a reader.
It was then that his eyes, his eyes filled with storms and pain and something else I couldn’t place, met mine.
This is such a bitter and beautiful description you give here.
He whispered. The world around us was so still. Just us, the burning sky and the unknown beneath the deathly thin line we walked.
You capture the moment very well here, but I think you should go into a new paragraph after the "he whispered". That would also give this moment more of that timelessness and calm that you radiate with the story.
Have fun writing!