How can I write a thesis for an essay on "Hills Like White Elephants"?

To come up with a thesis for Hemmingway’s “Hills Like White Elephants,” you need to decide what specific aspect of the story you want to discuss. There is a lot going on in this story. In the story, a couple is waiting for a train heading to Madrid. While Hemmingway does not clearly articulate the specific conflict, we know that there is something going on between the couple. The reader can infer that it revolves around the woman’s pregnancy; the man wants her to get an abortion, and the woman is hesitant about it and how it may affect their relationship.
Your goal in creating a thesis statement is to pick a certain aspect of the work you want to write about. Remember, that a thesis statement is not a summary of the plot; it entails something specific about the story such as how the setting and theme work together or the symbolism in the story and what it means.
One theme of “Hills Like White Elephants” is talking versus actually communicating. You could focus on the vague talk of the couple and discuss what they say versus what they actually mean.
A symbol in the story are white elephants. What do white elephants imply and why do you think Hemmingway chose this title?
Explore some aspect of the story that you find interesting, whether it has to do with the theme, the setting, or symbols and design a thesis statement from there.
Here's an example thesis statement: Ernest Hemmingway shows the distinction between talking and communicating through the couple's dialogue in his short story, "Hills Like White Elephants."

In order to come up with a thesis for Hemingway's "Hills Like White Elephants," you first need to determine what the story is about and what message Hemingway is trying to convey.
The story is about a couple waiting for a train at a train station. They are talking about the woman's pregnancy. The man wants her to get an abortion. She does not want to. There are clues this conflict is putting a great strain on their relationship, and probably reflects strains that were already there before the pregnancy brought the relationship to a crisis point.
With Hemingway, however, the problem is that he offers no explanation of what is going on. For example, he uses very plain words, such as "said," which don't offer information about how the couple is speaking to each other. So how do we know the couple is under a great deal of strain, angry, and saying the opposite of what they mean?
One way is repetition. For example, does the man repeat variations of "I wouldn't have you do it if you didn't want to" so often that he starts to sounds insincere?
Another way is through the bitter responses they give to what each other is saying. For example, when the man says, "Oh, cut it out," or when the girl says, "Can't we maybe stop talking," we might sense hostility.
A third way is symbolism: is sitting in a train station going nowhere symbolic of the relationship going nowhere?
If these seem to you like three signs of a dysfunctional, strained relationship, a thesis could be encompass how Hemingway reveals the unhappiness in this relationship through repetition, diction, and symbolism.