Thanks for the question! I think you might be interested in reading this Dear Sugar column to get a few ideas:
Dear Sugar is an advice column written by Cheryl Strayed, aka, master of breaking readers’ hearts. Writing about sad things is SO challenging, but she does it so beautifully. I think what makes her stories so beautiful is that she’s not afraid to explore pain.
Also, check out some of Joy Williams’s short stories. She explores a lot of conflicts between couples, and she’s a brilliant writer. One of my favorite stories of hers is “The Skater,” from her collection Escapes. It’s about a couple who are grieving the loss of their daughter, who died at age five, while also struggling to raise their living daughter, who is now five. It’s such a gorgeous story, and it captures the dynamic in the family so well.
Good luck! Thanks for reading!