strchr() finding '\n' where there seemingly is none

I'm using a modified fgets() function called s_gets() that removes a newline from input or discards any of the remaining characters in the input buffer. It looks like the following;

char *s_gets(char *str, int n, FILE *pf) {

    char *ret_val;
    char *find;

    ret_val = fgets(str, n, pf);
    if (ret_val) {
        find = strchr(str, '\n');
        if (find) {
            puts("Newline was found.");
            printf("Character before \\n is %c\n", *(find - 1));
            *find = '\0';
        } else {
            while (getchar() != '\n')
                continue;
        }
    }
    return ret_val;
}

When I use this function and pass it a FILE* to a file containing just the string apple on a single line, the puts() inside the if clause runs and the printf() statement prints Character before \n is e. My question is where is this mysterious newline coming from? Does this have anything to do with EOF? I'm compiling this with Apple LLVM version 10.0.0 (clang-1000.10.44.2) on macOS 10.14.

Even if the string "apple" is written on a single line, a newline character is automatically added to the end of that line by the editor (gedit for example). That's why you see it.

PS: As rici mentioned: Why should text files end with a newline?