Edwina Kwong wasn't expecting anything story-worthy out of her seventh year at Hogwarts. If there was a book series or a movie made about anybody at Hogwarts, she wouldn't be the protagonist. Probably not even the sidekick. More like the unnamed extra in the back of potions class. Demetrius Scamander wanted to leave Hogwarts having done something extraordinary (beyond winning the Hogwarts Quidditch Cup and acing his NEWTs, of course). So he agrees to assist Edwina in brewing a love potion for her crush. But of course, when it's true love, Amortentia isn't necessary.