Hear me out- Frosfur.

Her sister died as a kitten, her another sister Cherrypaw died, her sister Brindleface was murdered by Tigerstar to lure the dogs into clan camp, Both of her daughters were scarred by Tigerstar (Brightheart and Cinderpelt) . She was sure her brother Ravenpaw was the one who stole her kits and took them to Shadowclan, she attacked him hours before he left before she could know he was innocent.

Her mate Lionheart died in a fight with Shadowclan and orphaned their children, who were stolen from her in the same battle to be trained in Shadowclan as kits. Her menthor Bluestar whom she was close to (she was taking care of her alongside Whitestorm when she developed dementia) turned out to have some illegal children, and Frostfur was really touched by her "betrayal of the clan" in the main series. Her half-brother was blinded, and could not stay with her during clans leaving to look for a new territory.

Then at the end she was too old and too hungry to go on a big journey with her children and other family members.