In the epic I am writing, the protagonist and deuteragonist are sent on a mission by a king to save his daughter kidnapped by mercenaries of the evil empire. They save her, but the deuteragonist begins to develop feelings for her. They eventually start to date, fall in love, but then there's the bad news: She gets killed.
For I just narrated this is merely a long sidequest. This is also meant as character growth for the deuteragonist, and she eventually gets another girlfriend later on in the story. Problem is, I am trying to figure out how to write a love interest who, while only there for a short time, still is meaningful and can make the audience sad once they die. For other problems involved:
If you already noticed, this storyline is guilty of the Bury Your Gays trope. Then again, this story has a lot of lgbtq characters (including the protagonist), and many characters die throughout it, both gay and straight
Based on some other advice, there is the problem of introducing another love interest. This has already been solved, since the new one was introduced way in the beginning before the deuteragonist, and is well-written. This may not be a problem, but it is to address that this specific problem was already solved
The love interest gets brutally killed by the sadistic executioner, but for how it is, it seems like just a cheap way for character growth. The deuteragonist is trying to move on, but eventually encounters the executioner again.
How could a write a short-term love interest, so that they are still a fully-dimensional character AND have a death that actually makes the audience sad and feel bad?