About the fridging question:
Maybe you can give the dead gf more narrative impact by having her family or friends continue to talk about her and her ambitions or troubles throughout the narrative, proving that she wasn't just important to the lead character. You could also mention projects she worked on that go undone, changing the rest of the world too, like a garden that is now overgrown or craft supplies still in their packages. It can allow you to highlight the tragedy without focusing on the lead ig.
Hmm, that’s a good point, I am still at the starting stages of the story but having it be clear that she affected the lives of all the character who knew her, not just the main character would definitely help to avoid making her death a fridging