One possible element could be unrequited love. Maybe the Valkyrie fell in love with a mortal, but due to her divine nature and the rules of the cosmos, they couldn't be together.
It could also involve the death of a close companion. Valkyries are part of a group in Norse mythology. If one of her Valkyrie sisters was killed in a battle or by some other means, it would be a great source of sadness. Also, if she was blamed for the death of someone she was supposed to protect in battle, that would weigh heavily on her and make for a very sad story.
Maybe a rocket explosion during launch is part of it.
It could involve the mudbray being sick.
Sure. It could be a financial struggle. Maybe James lost his job and couldn't support his family.
One possible element could be unrequited love. Maybe Rekful fell in love with someone who didn't feel the same way, which can be a really sad situation.
One possible element could be loneliness. Maybe Black Sherif is all alone in his struggles, with no one to turn to.
Here's one. There was a noob in a dance class. They were excited to learn a new dance style. However, they had two left feet. The other students were much better and they often got made fun of by some mean classmates. They started to doubt themselves and felt really sad about their inability to catch up with the others.
Sure. There was a hamster named Charlie. Charlie's owner got a new pet, a cat. The cat was always trying to get to Charlie's cage. Charlie was so frightened all the time. Eventually, the constant stress made Charlie sick and he passed away. It was a sad end for poor Charlie.
Sure. A possible 'flamingo sad story' could be that a young flamingo got lost during a migration. It was separated from its family and the flock it was traveling with. Alone and disoriented, it faced many difficulties. It had to search for food on its own in unfamiliar territories, and was constantly in danger from predators. It was a very sad situation for the poor flamingo.
A soldier was sent to a far - away war - torn country. There, he witnessed the death and destruction every day. When he finally came back home, he couldn't adjust to the normal life. He was haunted by the memories of the war, that's a sad story.
One possible story could be that a family used to go to McDonald's every Sunday after church as a tradition. But then the local McDonald's was sold and the new owner changed the interior completely, removed some of the classic play area for kids, and the family no longer felt the same warmth and familiarity, so they stopped going. It was sad for them as it was a part of their family routine for years.